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Radiation

Primary Care Corner with Geoffrey Modest MD: Management of incidental pulmonary nodules

10 May, 17 | by

by Dr Geoffrey Modest

​The Fleischner Society guidelines for the management of incidental pulmonary nodules found on CT scans was just updated, involving international input from radiologists, pulmonologists, surgeons, pathologists (see doi:10.1148/radiol.2017161659​).

 

Details:

–the guidelines refer to incidental pulmonary nodules found by CT scan in those >35yo, not for patients at high risk (eg in those with cancer who might have mets, or those getting CTs for screening purposes)

–the minimum threshold size leading to  recommendation for nodule follow-up is if the estimated cancer risk is >1% (arbitrarily chosen)

–follow-up CTs should use low-radiation techniques, no more than 3 mGy in a standard sized person, in order to reduce radiation exposure, esp in patients likely to receive many of them.

 

Single solid nodules

— <6 mm (a larger size than prior guidelines): no further follow-up studies (grade 1C, strong recommendation, low- or very-low quality of evidence). Those at higher risk (see below), such as suspicious morphology or upper lobe location has optional recommendation to repeat CT but not before 12 months (small risk by waiting this long and earlier study might provide false reassurance)

— 6-8mm and low clinical risk (see below): follow-up 6-12 months, depending on size, morphology and patient preference (grade 1C, strong recommendation, low- or very-low quality of evidence​). usually one follow-up exam is sufficient, though optional one at 18-24 months. For those at higher risk, this additional 18-24 month follow-up is recommended.  (strong recommendation, moderate quality of evidence​)​. average risk of cancer 0.5-2%

— >8mm: same recommendation independent of risk: CT at 3 months, PET/CT, or tissue sampling (grade 1A, strong recommendation, high quality of evidence). average risk of cancer 3%

Multiple solid nodules

–dominant nodule <6mm: same as with single (Grade 2B, weak recommendation, moderate quality of evidence​)​.

–6-8 mm: same as with single, but initial follow-up CT at 3-6 months (optional follow-up at 18-24 months if low risk, recommended if high risk). Grade 1B, strong recommendation, moderate quality of evidence​​.

–>8 mm: same as 6-8mm

Single subsolid nodules

–ground glass nodule: <6mm, no routine follow-up; >6mm, CT at 6-12 months to confirm persistence, then every 2 years for 5 years​. (grade 1B; strong recommendation, moderate-quality evidence). Approximately 10% grow and 1% progress to adenocarcinoma, in a study done in Asian population.

–part solid nodule: <6mm, no routine follow-up; >6mm, CT at 3-6 months to confirm persistence (could be infectious and resolve). If solid component remains <6mm, annual CT for 5 years  (grade 1C; strong recommendation, low- or very-low-quality evidence). If solid component >6mm, highly suspicious for cancer (grade 1B; strong recommendation, moderate quality evidence.)

Multiple subsolid nodules

–<6mm: CT at 3-6 months. If stable, consider repeat at 2 and 4 years (grade 1C; strong recommendation, low- or very-low-quality evidence)

–>6mm: CT at 3-6 months. if persistent, consider diagnosis of multiple primary adenocarcinomas (grade 1C; strong recommendation, low- or very-low-quality evidence). subsequent management depends on most suspicious nodule.

 

risk factors for malignancy:

–nodule size is the dominant risk factor

–nodules are classified as solid, pure ground glass, and part-solid. BUT huge inter- and intra-observer disagreements (correct classification of nodules as solid or sub-solid was found in only 58% of cases!!). Those with marginal spiculation are more likely to be malignant (OR 2.2-2.5), though this is not really a binary finding, and no threshold of the degree of spiculation has been defined

–nodule location: upper lobes, and esp right upper lobe, more likely to be cancer, with odds ratio of about 2.0  Adenocarcinomas and mets are more likely peripheral, and squamous cell cancers are more near the hila. Small nodules in perifussural or subpleural areas often are lymph nodes

–nodule multiplicity: increased risk of cancer as number of nodules increases from 1 to 4, but decreases with >4 (more likely prior granulomatous infection)

–nodule growth rate: solid cancers double their volume (a 26% increase in diameter) in 100-400 days; subsolid nodules (eg, primary adenocarcinomas) have average doubling times of 3-5 years: hence the longer follow-up time for those with subsolid nodules

–emphysema/fibrosis: emphysema is independent risk factor for cancer. Old studies found about 3x increase. NLST  (National Lung Screening Trial, which led to current screening recommendations for smokers) found incidence of 25 cancers/1000 screened in those with emphysema and 7.5/1000 in those without. Both emphysema-predominant COPD and increasing severity of centrilobular emphysema increase the risk of cancer. As does pulmonary fibrosis (esp idiopathic pulmonary fibrosis, with HR 4.2)

​–age/demographics: rare <40yo, and increases each decade of life. Women may be at higher risk in a few studies: esp if lower BMI and lower educational level, but also a higher cancer risk in women with nonsolid nodules. Family history  is a risk factor both in smokers and never-smokers, with RR 1.5-1.8 if an affected sibling. Also higher in black men and native Hawaiian men at lower levels of smoking.

–tobacco/exposures. 10- to 35-fold increased risk in smokers. passive smokers also with increased risk, but less so. smoking mostly associated with squamous cell cancers. incidence of adenocarcinomas is increasing over time, esp for female nonsmokers, but unclear effect of smoking on this and smoking not included as a risk factor for adenocarcinomas. other inhaled carcinogens noted as cancer risk factors include asbestos, uranium and radon. [silicosis may be, but not shown conclusively, per my reading. similar with beryllium exposure. and, no doubt, others]

–the categories of risk used in this guideline are from the American College of Chest Physicians (these are spelled out, with a mathematical equation including the variety of risk factors:

–low-risk: estimated cancer risk (<5%), found typically in those of young age, less smoking, smaller nodule size, regular margins, and location other than upper lobe

–high risk (>5%), more often if older age, heavy smoking, larger nodule size, irregular or spiculated margins, and upper lobe location

–one not-so-uncommon clinical situation is the patient who has an abdominal CT, where the CT finds a small lung nodule (<6mm), but only the lower part of the lungs is visualized. If patient is low risk, no further follow-up recommended. If intermediate size (6-8mm), follow-up CT of the complete chest after 3-12 months depending on clinical risk.  If larger nodule or suspicious characteristics, full chest CT right away for further evaluation

 

Commentary:

–with increasing use of CT scans, lots of lung nodules are found. in US adults between 2006-14, more than 4.8 million had at least one chest CT, with >1.5 million nodules identified, and 63K lung cancers diagnosed within 2 years.

–I would personally include as higher risk any patients with industrial exposures esp if there is evidence of distorted lung parenchyma (eg fibrosis, as by silicosis), especially since other causes of fibrosis are higher risk (emphysema, idiopathic pulmonary fibrosis). and I would be more inclined to follow them more closely, as well as caution them about avoiding any other exposures more aggressively (smoking, etc).

–they do not mention HIV in this guideline (they refer to immunocompromise as creating higher likelihood of infection, no mention of cancer), but there are observational studies of 2- to 4-fold increased risk of lung cancer at younger age and lower smoking exposure: I had a patient who was an elite controller, who had an undetectable viral load, high CD4 count off any antiretroviral meds, minimal smoking history, but who died in his late 40s from lung cancer. My review of the literature found this phenomenon not so uncommon, even in patients with good immunologic response to antiretrovirals.  so I would add HIV, controlled or not, as potential risk factor

–I am very concerned about radiation exposure (as per many prior blogs). Above they mention that the repeat CT scans done should produce only 3 mGy of radiation exposure. LDCT, low-dose CT used for screening smokers, is 1.5 mSv, which from my search is the same as 1.5 mGy, whereas a diagnostic chest CT is about 7-8 mGy, and a chest xray about 0.1 mGy. So the recommended radiation dose for the follow-up repeat CT is less than 1/2 that of a regular diagnostic CT. I’m not sure exactly what that means. Is the follow-up CT different from a diagnostic CT?? Or are they recommending new CT scanners which deliver less radiation, but may not be available in many places (and might limit the generalizability or utility of their algorithm, since more cancers may be created by the higher radiation exposure)? There was an article about a new Toshiba CT scanner which delivers around 4 mGY: see https://www.technologyreview.com/s/510861/ct-scanner-delivers-less-radiation/​ , which may be what they are referring to….

–BUT, one concern I have is that the additional radiation exposure from multiple CTs (even from lower radiation ones) might have an even higher risk of causing cancer in patients with baseline abnormal lungs. The data on radiation exposure and cancer, from what I can find, is largely mathematical modeling based on people with normal lungs (eg Einstein AJ JAMA 2007; 298: 317, as well as here , here , and here). My guess, though not addressed in anything I have seen, is that those with diseased lungs are at higher risk of radiation-related lung cancer, and that risk may be much higher than estimates from the current mathematical models of people with normal lungs (eg, maybe the underlying lung pathology is associated with inflammation and fibrosis which is associated with significant chromosomal damage, etc, which puts the lungs at higher cancer risk from further damage by radiation??? sort of a multiple-hit theory??)

 

So, I think this guideline is helpful for us in primary care. Given the rather low bar to get CT scans these days and the frequent finding of difficult-to-interpret incidental “abnormalities” found, it is useful to have some sense of how to interpret and follow the findings, and why. of course, there are real concerns about the radiation exposure, but at least these guidelines are more lenient than prior ones (larger size cutpoint of when to do followup CTs, and less aggressive followup than before)​

 

 

Primary Care Corner with Geoffrey Modest MD: Radiologist Variability in Mammography Readings

13 Oct, 16 | by EBM

By Dr. Geoffrey Modest

A recent article revealed the dramatic variability in radiologists’ interpretations of mammographic breast density (see Sprague BL. Ann Intern Med 2016; 165: 457). Determining breast density accurately is certainly important because increased breast density leads to difficulty in reading mammograms and is an independent risk factor for breast cancer. In this light, one prerequisite for us in primary care is that the radiologic determination of breast density is consistent and accurate. But, details, from an NIH supported study:

  • Data from 216,783 screening mammograms from 145,123 women aged 40 to 89 were included, from 30 radiology facilities within three breast cancer screening research centers of the Population-based Research Optimizing Screening through Personalized Regimens (PROSPR) consortium.
  • 83 radiologists were involved; each interpreted at least 500 screening mammograms from 2011-3, using the BIRADS reporting system, along with patients age, race, and BMI

Results:

  • 9% of mammograms were rated as showing dense breasts
  • Across radiologists, the finding of dense breasts ranged from 6.3% to 84.5% (median 38.7%, interquartile range 28.9% to 50.9%). !!!!
  • Variation in breast density assessment was pervasive in all but the most extreme patient age and BMI combinations
  • Among women with consecutive mammograms interpreted by different radiologists, 17.2% had discordant assessments of breast density.

Commentary:

  • One of the scariest issues to me as a clinician is that I need to rely on an accurate interpretation of medical tests in order to inform my patient management. The sheer magnitude of the variation in breast density assessment is quite striking.
  • There are also other studies, mostly 10-20 years old, showing that the general radiologic interpretation of mammograms has considerable variability as well.
  • There are certainly other tests that have significant variability andhighlight this issue more broadly — for example finding significant spine MRI abnormalities in totally asymptomatic patients:
    • One study (see Jensen MC. N Engl J Med 1994; 331: 69) looked at 98 people without back pain, where their MRI scans were interpreted by two experienced neuroradiologists at the Cleveland Clinic, finding that 52% had a bulge in at least one intervertebral disc, 27% had a protrusion, and 1% had an extrusion. 38% had multilevel abnormalities. Only 36% had a normal MRI.
    • A systematic review (see Brinjikji W. AJNR2015 36: 811-816) found dramatic MRI or CT changes in asymptomatic people, which increased with age.  For example, the prevalence of disc degeneration went from 37% at age 20 to 96% at age 80, bulges went from 30% at age 20 to 84% at age 80, disc protrusion from 29% age 20 to 43% at age 80, annular fissure from 19% age 20 to 29% at age 80.  so, lots and lots of impressive disc changes even in asymptomatic 20 year olds……
  • Another issue, which we tend to understand more intuitively, is that of ultrasounds, which are clearly operator-dependent. But we had a patient with chronic hepatitis B, who had a “normal” screening RUQ ultrasound for hepatocellular cancer, but a CT revealed a 9cm cancer!! I spoke with a trusted hepatologist who commented that he used a CT to scan to screen for really high-risk patients because of the variability of ultrasounds (though that is not exactly a clear-cut, or generally accepted algorithm….)
  • One major concern about over-reading breast density (as well as potentially scaring patients that they might be at higher breast cancer risk) is that this findingoften leads to further studies such as ultrasound, digital breast tomosynthesis, and MRI examination (though there is minimal evidence to support these tests, and they may well lead to unnecessary biopsies, more radiation exposure, etc. And the USPSTF formally gives these procedures an “I” rating, for insufficient evidence)
  • And, another issue:  half of the United States has legislation currently requiring disclosure of mammographic breast density, in some cases advising women to discuss supplemental screening tests with their providers if they have dense breasts (again without supportive medical evidence). And even theFDA is considering a legislative requirement to report breast density information to patients. I think there is a real concern about non-medical legislators enacting medical legislation, where legislators may be swayed by patients pleading for unproved treatments, perhaps with the support of an “expert witness”. Or, perhaps the legislature decides to require a certain treatment based on small or flawed studies, writes the treatment into law, but then new and better studies contradict this legislative imperative. One recent example is in Massachusetts, where a law was passed requiring insurance to cover long-term antibiotic therapy for chronic Lyme disease, though several studies, including a new one (see Berende . N Engl J Med2016;374:1209-1220), have not found benefit from long-term antibiotics. Or, in the past, there has been legislation supporting the availability of bone marrow transplants for women with breast cancer, but without any evidence of benefit (and pretty clear harm). I do realize that there have been egregious, inappropriate treatment denials by some health insurers in the past which has led to some of this legislation and public/medical community outrage. But legislating medical diagnostics and therapies is fraught…..
  • So, this inconsistency/unreliability in breast density interpretation may subject many people to potentially dangerous interventions. I think it is really important that we as clinicians understand that many procedures we order are subject to large variability, as above. So, what can we do??
    • Whenever possible, we should interpret these “objective” data in the context of the clinical situation of the patient, and not always reflexively respond to the test results (it is just another piece of data, such as from the history or physical, which should be put in the overall gestalt of what is going on with the patient). Of course, some of these objective findings, even unsuspected, may be very important and not dismissed (e.g., the incidental finding of early pancreatic or renal cancers).
    • Maybe we should consider getting second opinions more often than we currently do, to assess interobserver agreement
    • Perhaps there should be triggers in place for certain findings (such as dense breasts on mammogram), requiring a blinded read by another radiologist, or?? always having mammograms automatically re-read by another radiologist??, or having an automatic second-read whenever a radiologist comments “should be repeated in 3-6 months by another test”, which puts the medicolegal imperative on us in primary care to do yet another test with potentially more radiation exposure, cost, possible unnecessary procedures, etc.
    • Perhaps there needs to be much more transparency in the system overall, maybe requiring those reporting on these results to have regular standardized testing themselves and posting the results (sort of like requiring hospitals to report their C-section rates).
    • Perhaps we need a good computer program????
  • I realize this blog is more tangential than others, but i do think this issue of inconsistency in mammography reading does bring up a slew of general issues in clinical medicine…..

Primary Care Corner with Geoffrey Modest MD: Need Annual Low-Dose Chest CTs?

5 Apr, 16 | by EBM

By Dr. Geoffrey Modest

A retrospective cohort analysis of participants in the National Lung Screening Trial (NSLT), the trial that propelled forward low-dose lung CT (LDCT)​ screening in smokers, found that those with a negative initial LDCT actually had a much lower subsequent incidence of lung cancer and that annual screening may not be necessary (see doi.org/10.1016/ S1470-2045(15)00621-X​). See blogs at the end for details and my analysis of the NSLT study, and the perhaps overenthusiastic guidelines than ensued.

Details:

  • 26,231 people were screened, according to the criteria: aged 55-74, with at least a 30 pack-year history of cigarette smoking, and, if a former smoker, had quit within the past 15 years. They had 3 annual LDCT screens and were followed for 5 years after the last screen.
  • 19,066 (73%) had a negative initial screen

Results:

  • Those with a negative initial screen had a lower incidence of:
    • Lung cancer than the group as a whole (371.88/100K person-yrs, vs 661.23)
    • Lung cancer-related mortality than the group as a whole (185.82/100K person-yrs, vs 277.20)
  • ​The finding of lung cancer at the first annual LDCT screen in those with initially negative initial screen was:
    • 34% (62 screen-detected cancers out of 18,121 screens), which was much lower than on the initial screen of all participants, 1.0% (267 of 26,231)
  • The mathematical estimate was that if those with negative initial LDCT screens had skipped the first annual screen, at most 28 additional participants would have died from lung cancer (i.e., a rise in mortality from 185.82 to 212.14/100K person-yrs over the course of the trial).

So, this brings up a few points:

  • Not so shockingly, if you cull out those with lung cancer on the initial screen from those with normal screens, the pick-up of lung cancer the next year would be lower
  • Why might this be true?? Perhaps those smokers with normal looking lungs at the initial screen are actually different from the group who develop lung cancer. Perhaps there are factors beside the quantity of cigarettes smoked which matter… well, it turns out that an old study from 30 years ago, based on the Johns Hopkins Lung Project participants (one of the 3 early clinical trials looking at sputum cytology and CXR as a means to pickup early lung cancer in smokers), found that “among cigarette smokers, the presence of airways obstruction was more of an indicator for the subsequent development of lung cancer than was age or the level of smoking. The risk for lung cancer also increased in proportion to the degree of airways obstruction. These data suggest that smokers with ventilatory obstruction are at greater risk for lung cancer than are smokers without obstruction. ” (see Ann Intern Med 1987; 106: 512). And, in fact, emphysema in NSLT conferred a 96% increase in lung cancer risk in those with an initially negative LDCT
  • So, maybe there should be more risk stratification in doing LDCT screening. My real concern here is that radiation is bad for you. There is a potential creation of cancers by excessive radiation (and given the high false-positivity rate of LDCT, 39% in NSLT as mentioned in blogs below, the actual dose of radiation is on average about 4x higher, equivalent to a regular high-dose CT). And, I would imagine, it might well be that lungs that are adversely affected by smoking, perhaps those with COPD from tissue destruction and maybe with important changes in local defenses, may be even more susceptible to radiation-induced lung cancer (i.e., even more than the estimated one cancer death in 2500 screened). Perhaps assessing airway obstruction, as in the old Annals study above, would be useful (and spare lots of people from the potentially harmful effects of radiation)
  • And, besides, there is no biological reason to think that annual screening is the correct interval anyway, even if long-term screening were appropriate. It’s just that annual screening was arbitrarily chosen by NSLT (which, again from the perspective of this study, only did 3 screens, yet this was generalized in the recommendations to a whopping potential of 22 screens). And, by the way, as mentioned in prior blogs, though not statistically significant (perhaps from low numbers of cases and short-term followup), the NSLT pick-up rate for positive LDCT screens went from 27.3% in year 1 to 27.9% in year 2, then dropped to 16.8% in year 3. Would that continue to decrease? Are there subgroups where the decrease was more profound?​ These are really essential questions to answer in order to optimize screening in terms of the risk/benefit ratio.
  • But, the wholesale acceptance of annual LDCT by the USPSTF and by Medicare does put us at very significant medico-legal risk if someone develops lung cancer and were not screened (and it is hard to prove on an individual basis that one prevented a cancer by not screening). Just makes things harder for us to figure out what to do for our patients….

http://blogs.bmj.com/ebm/2015/01/24/primary-care-corner-with-geoffrey-modest-md-uspstf-lung-cancer-screening-revisited/ is a critical review of the NSLT and the US Preventative Services Task Force ​ recommendations, including that NSLT actually had decreasing pick-up of lung cancers on year 3 vs year 1 of the 3-year study

http://blogs.bmj.com/ebm/2015/02/18/primary-care-corner-with-geoffrey-modest-md-medicare-and-lung-ct-screening-of-smokers/ which reviews Medicare recommendations and highlights several points, including that screening for just 3 years is projected to create one cancer death per 2500 screened from radiation. And, per Medicare, patients could be subjected to 22 annual screens if they continue to smoke and we follow the letter of the guidelines.​

Primary Care Corner with Geoffrey Modest MD: Lung ultrasound to diagnose heart failure

4 Aug, 15 | by EBM

By: Dr. Geoffrey Modest

A potentially very useful multicenter study was just published finding that lung ultrasound (LUS) was better than chest xray (CXR) in the diagnosis of acute decompensated heart failure (ADHF) in patients presenting to the emergency room (ER) with dyspnea (see CHEST 2015; 148(1): 202 – 210). This is an increasingly common issue, with evidently very different therapeutic approaches depending on the etiology.

Details:

 –1005 patients from 7 Italian ERs presented with acute dyspnea, and the ER MD was asked to categorize the dyspnea diagnosis as either from ADHF or noncardiogenic dyspnea, based on their initial clinical assessment (this was not prescribed but left up to the ER MD, to simulate a real-world situation) and after LUS. All patients also had CXR’s. After patient discharge, independent reviewers  determined the cause of the dyspnea.

–544 (51.4%) patients were in community hospitals, 461 (45.9%) academic medical centers. Median age 77, 46.2% women, 41.8% smokers, 40.7% with COPD, 63.5% hypertensive, 20.2% with congestive heart failure (CHF), 25.8% with ischemic cardiomyopathy/CAD, 27.9% diabetic. Most on lots of meds. So, pretty sick group overall

Results:

–final diagnosis of ADHF was in 463 patients (46%), with very high agreement between the 2 physician adjudicators of the diagnosis.  81.7% of the patients were admitted to the hospital.

–clinical workup and LUS alone were much more accurate than CXR (p<0.01):

–I included below 2 of their summary figures. The one to the left is the summary sensitivity, specificity, etc in the whole group (top) and in those who had BNP/NT-pro-BNP sent. The  figure on the right is the ROC curves, showing that clinical evaluation plus LUS were remarkably accurate: they achieved sensitivity, specificity and AUC values for diagnosis of ADHF of 97.0%, 97.4%, and 0.972!!! CXR had sensitivity as low as 69.5% (which is higher than in some studies…..) — so, absence of CXR findings does not even come close to excluding a diagnosis of ADHF!!

–the net reclassification improvement (NRI), an estimate of the % of subjects moving from one diagnosis to another, of the LUS approach vs standard clinical workup was 19.1% (p<0.01)

–the accuracy of BNP/NT-pro-BNP values (available on subgroup of 486 patients) was significantly lower than the LUS approach (p<0.01): the sensitivity/specificity was 85%/61.7% with AUC of 0.733, again being not nearly as sensitive as LUS.

–there was near perfect intraobserver agreement in reading LUS (0.97) among experts, and a really good agreement (0.92) for ER MDs with limited LUS training (<10 examinations performed)

 untitled

untitled2

 One of the strengths of this study is that it incorporated the clinical pretest probability (the “LUS-implemented” approach), which was much more accurate than LUS alone, which was better than CXR (though, to be fair, they did not look at a “CXR-implemented approach”, but the stand-alone CXR was still really inferior to the stand-alone LUS).  In this study LUS was done as a rapid, bedside test, with a positive test for ADHF defined as “bilateral presence of 2 or more zones showing the presence of at least 3 B-lines: vertical, hyperechoic reverberation artifacts extending from the pleural line to the bottom of the screen”, these artifacts are presumably from interstitial fluid in the lung. This was a stricter definition of a “positive” LUS than in prior studies, which could explain the greater accuracy here — prior studies have found more limited LUS accuracy (as low as 54%) in ADHF diagnosis. One potential bias in this study is that the same MD who made the initial clinical diagnosis also performed the LUS and was therefore not blinded to the results of the clinical workup in interpreting the LUS.

So, bottom line: this study comes on the tail of one earlier this year showing better accuracy of LUS than CXR for pneumonia (see here). Together, these studies reinforce the potential to use a noninvasive and nonradiation-associated evaluation for both CHF and pneumonia. Although this was an ER-based study, it is likely to be applicable to patients who come into primary care with decompensated heart failure, though it would be great to have a community-based study done — the majority of patients with ADHF I see at the health center are not sent to the ER or admitted.  I treat these patients based on clinical assessment and CXR, with very close followup, and they do fine clinically. But I imagine that the availability of LUS would allow for a more assured diagnosis.

Primary Care Corner with Geoffrey Modest MD: Radiation exposure

29 Jan, 15 | by EBM

By: Dr. Geoffrey Modest 

As many of you know from being exposed to my rantings, I am very concerned about excessive iatrogenic radiation exposure. (I believe exposure to my rantings are less toxic than the radiation).

An article in JAMA looks at 6 integrated health care delivery systems with 1-2 millions people over 15 years. Effective doubling of radiation exposure in this period , esp with CT scans (increased 3-fold). Calculated anticipated 2% increased risk of cancer from this increased exposure (this may be an argument to dissuade some patients who seek a CT scan unnecessarily).

Primary Care Corner with Geoffrey Modest MD: CT scanning in kids and radiation exposure

29 Jan, 15 | by EBM

By: Dr. Geoffrey Modest

I will post an old blog:

The use of CT scans is increasing dramatically in kids. Data collected from 7 large HMOs in the US over 10 years (2001-2011) in kids <15yo, with 4.9M child-years of observation. One advance in this study is that they collected the actual technical parameters (radiation dose) used in diverse facilities.

Major findings:

— a doubling of CT scans done in kids –large variability of radiation dose per scan at different sites. highest dosages overall with abd/pelvic CTs (40% done for pain, 11% for r/o appendicitis, 6% for infection)
–Head CT was the most commonly done CT and increased 50%, though the % increase was highest in abd CT for children 5-14yo.
–using risk models (some based on the Japanese atomic bomb survivors, with those numbers of cancers being similar in a recent CT study), they calculated that:
–in kids under 5yo, those getting head scans (the most common) assoc with one solid cancer developing per 570 CTs in girls and 1350 CTs in boys, and one case of leukemia in 5000 scans (less in older kids);
–for abd/pelvic CT: 300 scans in girls and 670 scans in boys assoc with likely development of one solid tumor (not much difference by age)

So, not huge increased risk for an individual getting a scan (i.e., get one if really necessary), but in population overall, the annual pedi CT scan rate of about 4-9 million CTs/year leads to a large projected increase in cancer, on the order of 5000 cancers/yr. Some studies suggest that 1/3 of CT scans in kids are unnecessary, though changing this is sometimes difficult (we recently had a kid where we suggested doing an ultrasound as initial w/u for possible appendicitis, but the ER/surgeon insisted on CT scan). Also, the great variability in radiation dosage per test (which seems in part due to radiology techs not scaling down radiation exposure sufficiently in kids) needs to be reduced. the potential reduction in cancer by eliminating the unnecessary CTs and decreasing the radiation dosage per CT could decrease the cancer rate by more than 60%. Behavior change for us guys ain’t easy, but the good news is that after repeated battering, we are really doing better at not prescribing antibiotics for likely viral bronchitis, etc.

Primary Care Corner with Geoffrey Modest MD: Cardiac Imaging and Radiation Exposure

6 Nov, 14 | by EBM

The American Heart Association came out with a scientific statement to limit patient exposure to radiation (see here). It turns out (not surprisingly) that despite improved, lower-exposure technology, there has been a 6-fold increase in medical imaging radiation exposure from 1980 to the present, and that 40% comes from cardiovascular imaging and interventions. There is clearly a knowledge deficit: a 2004 study found that <50% of radiologists and 9% of ER docs were aware that CT scans could increase lifetime risk of cancer!!! Extrapolating from current data, women and younger individuals will have higher likelihood of cancer by a procedure, as depicted below (SPECT MPI = single-photon emission CT myocardial perfusion imaging, TC = technetium-99m; CTA = CT angiography).

graph1So, recommendations:

–All clinicians should know which cardiac imaging uses ionizing radiation and what are the typical radiation exposures (there are lots of publicly available sources: see their table 2)

–Those doing the procedures should use the best dose-optimization and minimization techniques (i.e. best images at lowest radiation exposure)

–Patients should be provided with key facts about the procedure, including radiation exposure, along with risks and benefits of alternative procedures when available

So, one example they give is of a patient scheduled for cardiac imaging for CAD evaluation, with the following decision tree:

–Is the study appropriate?

–If so, is imaging without radiation available and comparable?

–If yes, consider that imaging, especially in younger patients. Otherwise, can patient exercise?

— If not, consider CT angiography or PET, if available. If so, then consider SPECT (especially using lowest dose, >1 head, and high-sensitivity camera). If stress-only imaging, then use Tc99m (not thallium-201 which has greater radiation exposure and poorer spatial resolution).

The goal of this AHA statement is to minimize radiation exposure, especially in younger people and women who seem to have higher likelihood of developing cancer over time. Clearly, the benefits of an optimal study with ionizing radiation may well be important (though we should really make sure that the test is necessary and will potentially supply information which could change management) and we know that many-too-many studies are done. See Choosing Wisely, which notes that low-risk patients comprise 45% of unnecessary “screening”, where screening should be limited to diabetics >40 yo, people with peripheral artery disease, or those with >2% yearly risk of CAD event. We should preferentially choose tests which minimize radiation. It is incumbent on the cardiologists/radiologists to make sure their equipment is up-to-date, and provide the lowest radiation exposure possible, though it is not a bad idea for us to ask them/check around for the best alternatives.

Geoff

PC Corner with Dr. Geoffrey Modest: CT and radiation–another view

3 Feb, 14 | by EBM

i realize that i have spent a disproportionate amount of time writing about the risks of CT scan (and xray exposure in general). but there was a really good editorial in the NY times today by a cardiologist and radiologist (see http://www.nytimes.com/2014/01/31/opinion/we-are-giving-ourselves-cancer.html?ref=todayspaper). their points:

 

–cancer deaths are increasing relatively, as heart disease (the major killer) mortality has decreased over the decades

–medical radiation exposure has increased 6-fold from 1980s to 2006

–one in 10 americans get a CT scan every year (and many more than 1/yr), with radiation 100 to 1000 times higher than regular xray

–british study of kids exposed to multiple CTs found 3x incidence of leukemia and brain cancer

–? role of direct-to-consumer advertising or financial incentives of MDs.  though i would add here that xrays have become part of the “culture” and patient expectations: patients often come to me requesting an xray/CT etc, and i often need to spend significant amounts of time dissuading them of the need.

–Natl cancer institute in 2009 estimated that CT scans resulted in 29,000 excess cancer cases, and 14,500 excess cancer deaths. these editorialists estimate that 3-5% of all future cancers may be from medical imaging

–there is large variance of dose/xray from one institution to another

–they promote using the Choosing Wisely website to help patients (and providers) decrease xray utilization

 

one particular concern, not mentioned above, is the new USPSTF recommendation to do annual low-dose CT screening of all current smokers aged 55-80 with smoking history of >30 pack-years, or those who stopped smoking within the past 15 year. this was based on the natl lung screening trial, which found that annual low dose CT screening (for only 3 years, but then followed another 3.5 yrs) in those aged 55-74 (for some reason USPSTF increased the age to 80!!) decreased mortality by 20% (which translated to absolute benefit of only 62 deaths/100,000 person-years), but with a 25% false positive screening rate leading to more radiologic procedures (so that on average the low-dose CT was actually equal to that of a regular CT with 8mSv radiation exposure, and that this degree of radiation exposure would create one cancer in 2500 screening people. (see prior email/blog for details)

 

and, the increased number of screens (up to 25 annual screens, if the person kept smoking), would undoubtedly augment many of these numbers (eg, adverse effects of continued screening, including psych; probably increased false positives with more biopsies and potential problems esp as people get older and likely have more COPD; and undoubtedly more iatrogenic cancers…..)

 

geoff

Primary Care Corner with Geoffrey Modest: Diagnostic Radiation Exposure

19 Jul, 13 | by EBM

JAMA. 2012;307(22):2400-2409

as many of you know from being exposed to my rantings, i am very concerned about excessive iatrogenic radiation exposure. (i believe exposure to my rantings are less toxic than the radiation).

article in jama looks at 6 integrated health care delivery systems with 1-2 million people over 15 years. effective doubling of radiation exposure in this period , esp with CT scans (increased 3-fold). calculated anticipated 2% increased risk of cancer from this increased exposure (this may be an argument to dissuade some patients who seek a CT scan unnecessarily).

geoff

Primary Care Corner with Geoffrey Modest: Choosing (Tests) Wisely…

19 Jul, 13 | by EBM

http://www.choosingwisely.org/doctor-patient-lists/

Choosing-wisely came out with long list of suggestions (this is the group who came out with the radiology suggestions last year). These suggestions come from many different specialty societies, each giving their top 5. Basically these are general guidelines to decrease testing overall and do not mean that these tests are not appropriate for certain individuals.  I will summarize some of the most relevant suggestions below. There are some minor differences between the different societies.

— avoid doing indiscriminate battery of IgE testing for allergies.  Should do targeted and specific testing only.

— no sinus CT or antibiotics for uncomplicated rhinosinusitis.

— no extensive workup for chronic urticaria (e.g. allergy testing) unless there is a clear history pointing to a specific allergy

— they suggest routine spirometry for asthma, as recommended by the various asthma/pulm societies, to make sure the diagnosis is correct.

— no DEXA scans in women less than 65 and men less than 70 as a routine screen.

— no annual EKGs and asymptomatic patients

— Pap smear as per the routine that I sent out before, including stopping at age 65 unless the patient is high risk

— no carotid artery screening if the patient is asymptomatic.

— no feeding tubes in patients with advanced dementia

— do not delay palliative care even if the patient is getting a disease-directed treatment

— no carotid artery evaluation if the patient has simple syncope and a normal neurologic exam

— avoid opiates and barbiturates for migraine except as a last resort

— preop evaluation for eye surgery should be targeted. Eg, EKG the patient has heart disease, fingerstick if patient has diabetes, potassium if the patient is on a diuretic

— not give topical antibiotics for viral conjunctivitis

— did not do a head CT in kids with minor head injuries and normal neurologic exams

— do not do routine abdominal CTs in kids with abdominal pain.  Low yield and radiation exposure is significant

— do not do stress cardiac imaging/advanced noninvasive imaging if the patient is without cardiac disease (though they do suggest doing an diabetics greater than age 40, patients with PAD, and patient was greater than 2% annual risk of heart disease — though I think these are too aggressive and even the American Diabetes Association has backed off from routine imaging in diabetics greater than 40)

— no need to do routine follow-up echocardiograms in patients with mild asymptomatic native valvular heart disease

— no need for routine preop chest x-rays

— in child with suspected appendicitis, do an ultrasound as the initial evaluation

— do not check Lyme serology for patients with diffuse musculoskeletal pain unless there is a known exposure and suggestive exam (i.e. it is not appropriate in general for people with just arthralgias)

— do not routinely get DEXA scans at intervals of less than every two years (though the patient reports we get often suggest getting them in one to two years)

— for GERD treatment, titrate to the lowest effective dose of the least potent medication

— do not get routine CT scans for patient with functional abdominal pain (per the ROME III criteria) unless there is a major change in symptoms

— avoid antipsychotics as a first line therapy for patients with behavior problems or psychiatric symptoms with dementia

— avoid increasing diabetic medications in patients over 65 to achieve an A1c of less than 7.5

— in areas where there is widespread vitamin D deficiency (like here), it is prudent just to give vitamins instead of testing everyone

— is unnecessary to check creatinine for patients with benign prostatic hypertrophy

— ultrasound is not a sensitive test for boys with cryptorchidism

— did not order coronary artery calcium scoring on patients with known CAD, for preop of relation for any surgery, or for screening and low risk patients except those with a family history of premature atherosclerosis

— do not use routine bronchodilators in children with bronchiolitis

— do not use routine acid suppressive therapies in infants with GERD

— do not screen for renal artery stenosis in patients who do not have resistant hypertension and have normal renal function, even if there is a history of atherosclerotic disease.

Note: These are many of the recommendations, with some supporting documentation.  Part of the rationale is a undoubtedly cost-saving, but part of it is also to minimize adverse effects of testing, including unnecessary radiation exposure.  Again, you should do what you think is right for the patient in front of you, but should not feel it is necessary to do the above tests routinely.

Geoff

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