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Incidental gonorrhoea screening in the general population via dual NAAT is no benefit

12 Jun, 15 | by Leslie Goode, Blogmaster

Fifer & Ison (STIs) express concern over the use of the “dual” nucleic acid amplification tests (NAATs) for the detection of chlamydia and gonorrhoea in the context of chlamydia screening in the UK.  Additional testing for gonorrhoea, when the real target is chlamydia, does not necessarily confer an additional net benefit.   This is because even a high specificity test such as Cobas 4800 (Perry & Corden (STIs); Rockett & Limnios (STIs)) will generate a high proportion of false positives when the infection tested for has extremely low prevalence, as in the  case of gonorrhoea in the general population.  And the potential disbenefit of the additional test in terms of the psychological impact, and the impact on relationships, of false positive diagnoses could easily outweigh the medical benefit represented by the diagnoses which are accurate (Dixon-Woods & Shukla (STIs); McCaffery & Wardle (STIs)).

The potential impact of the adoption of the dual NAAT as a stand-alone test – if not confirmed by further testing using either a second NAAT or else culture – is illustrated by a recent Australian study published in the Medical Journal of Australia (MJA).  Chow & Fairley perform a retrospective analysis of insurance and notification data from Melbourne over the years 2008-2013.  They seek to demonstrate that the apparent rise in identified gonorrhoea cases amongst the general female – non-indigenous – population (from 98 to 343) is at least partly an “artefact” of the growing employment by laboratories of the dual NAAT.  They do this by eliminating the alternative possibility of a genuine increase in gonorrhoea in the general population.  To this purpose they use their data to investigate changes in the proportion of positive dual NAAT gonorrhoea diagnoses to the number of dual NAAT test ordered, over the period during which dual NAATs were being introduced.  They also investigate rates of positive gonorrhoea diagnoses over this period at a “sentinel” clinic in Victoria where culture alone was used as a means ofgGonorrhea diagnosis.  They find that the proportion of positive dual NAAT diagnoses in Victoria remained relatively constant over time (around 0.2-0.3%), as did the proportion of positive culture diagnoses at the Melbourne clinic (around 0.4-0.6%).  Of 25 untreated women who had a positive NAAT result for gonorrhoea and were referred to the Melbourne clinic, only 10/25 were confirmed by culture.  The authors comment that this is in line with what might be expected in the light of the published specificity of the various NAAT tests employed.

C&F recommend that laboratories suppress gonorrhoea diagnoses from the dual NAATs.  An MJA editorial in the same issue questions the feasibility of this.  Instead, the editors propose that the NAAT should, in the case of Gonorrhoea, be used as either a triage, with positive diagnoses confirmed by culture, or as an add-on where high prevalence populations are first tested by culture.  They also consider the possibility of confirming the initial NAAT with a NAAT using a different target.  However, they come down in favour of retaining culture in the diagnostic pathway on account of its value as a means of assessing resistance.  They also question whether even the double NAAT would guarantee adequate predictive value in very low prevalence populations.

Evidently, further studies are required.

Why Tanzania seems unlikely to meet UNAIDS targets for HIV/AIDS prevention.

12 Jun, 15 | by Leslie Goode, Blogmaster

The UNAIDS 90-90-90 Target has set the goal that, by 2020, 90% of the HIV infected should know their status, 90% of those diagnosed should be in treatment, and 90% of those in treatment should achieve viral suppression.  The  UNAIDS GAP Report (2014) presses the need for countries to achieve a major redeployment of effort and resources towards tackling HIV among at-risk populations with a view to achieving that target (UNAIDS (STI/blog)).

Redeployment, a report by Congressional staff delegates on a visit to Tanzania hosted by the Infectious Diseases Society of America’s (IDSA) Global Education and Research Foundation gives a detailed account of the practical problems facing the attempt to make such ambitions a reality on the ground – even where UNAIDS recommendations are embedded in official government planning policy.  Evidence from visits of the staff delegates to Dar-es-Salaam, Zanzibar and Mbeya in the rural highlands is illustrated with well-chosen photographs.   These problems fall into three general categories.

First, there is a human resource problem.  At present, there is a 65% vacancy rate for health-care positions in the public sector.  According to the government figures, health workforce capacities have steadily declined from 67,000 in 1994/5 to 54,245 in 2002 to 48,000 in 2015.  The PEPFAR (President’s Emergency Plan For AIDS Relief) operational plan attributes this in some measure to gaps in Tanzania’s education capacities with large classes and poorly trained teachers, leading to pupils leaving school without adequate study, problem solving and analytic skills.

As regards redeployment of these limited resources in line with UNAIDS recommendations, this is hindered by the fact that at risk groups may be criminalized (e.g. drug-users, sex workers, MSM) and are certainly stigmatized.  Much of the outreach to them is through civil society organizations.  While the government has policies to support and defend their efforts, there is little in the way of financial investment.  Civil society organizations are hampered by the largely voluntary nature of their workforce, and the absence of adequate data concerning the size and whereabouts of at-risk populations (though it is estimated that between 2010 and 2015 the number of IDU rose from 25,000 to 50,000).  The prison population seems to be altogether inaccessible.

Thirdly, HIV transmitted to children born to infected mothers is often ignored, and the number of adolescents dying of AIDS has risen by a third since 2005.  This is partly because stigma surrounding a disease associated with IDUs, sex-workers MSM prevents parents from seeking diagnoses for their children.  The situation is not helped be the frequently poor state of record-keeping with no digitalization and folders “jammed into, stacked on top of, and spilling out of record cabinets”.

Though no doubt inadequate, data on “at risk” populations is not altogether absent.  Studies published in STI journal relevant to populations in specific places visited by delegates include an evaluation of surveys of MSM in Zanzibar, Haji & Kibona (STIs), and a discussion of the socio-demographic context of the epidemic in Mbeya, Riedner & Groskurth (STIs), focussing on female bar-workers.  As a poor but high-mobility rural population, Mbeya appears to share some socio-demographic characteristics with Mzanza province in the NW (bordering Lake Victoria) which has figured in a number of studies at the beginning of the last decade.  A number of these focus on barmaids as a particularly high-risk population (Hoffmann & Hoelscher(STIs); Boerma & Mwaluko (STIs); Bloom & Boerma (STIs)).

 

Increased HIV infectivity in the acute phase of infection may be a less important factor in HIV transmission than we thought

12 Jun, 15 | by Leslie Goode, Blogmaster

Assessing, as far as we can, the preventative impact of ART on HIV transmission dynamics is evidently very important – both to inform judgments about ART initiation (Wayal & Hart (STI); Cohen (STI)), and also, at the policy level, to be able to evaluate the possible preventative gains of ART scale-up (Shafer & White (STI); Boily & Mishra (STI)).   One important piece of the jigsaw is the impact of ART on sexual behaviour.  This has been discussed by a number of recent studies (Wayal & Hart (STI); Hogben & Ford (STI); Shafer & White (STI)).  Another piece of the jigsaw is the impact of ART on HIV infectivity.  Of particular concern here are the relatively high levels of infectivity that occur in the period immediately after infection.  In view of this, investigators have stressed the importance of the earliest possible initiation of therapy, if the full preventative benefits of ART are to be enjoyed (Cohen (STI)).

The recent study, Bellan & Meyers (B&M), addresses itself to this second, important but potentially less easily investigable piece of the jigsaw. They observe that investigators have tended to proceed on the basis of the known relationship between viral load and infectivity. Empirical evidence of relative infectivity of acute versus chronic phases of the infection is practically unobtainable, for various reasons.  For a start, newly-infected individuals are rarely diagnosed in the acute phase and, if infected by stable partners may provide no evidence on onward tradition; if susceptible non-infected partners are at risk, then, clearly, ethical guidelines dictate that further transmission be stopped – not investigated.  According to B&M, most subsequent studies have relied for direct epidemiological measurement of acute phase infectivity and duration on a retrospective cohort in Rakai, Uganda (Wawer & Quinn; Hollingsworth & Fraser). B&M reassess previous analyses of this evidence.  They find significant bias – especially in two areas.  The first has to do with the neglect of the contribution to total risk of couples who were censored from the cohort owing to couple dissolution, loss to follow-up or study termination.  The second concerns the extent to which some of the estimated difference in risk between the acute and chronic phases may reflect heterogeneity in the risk behaviour of those couples entering the study sero-discordant, as against those entering it sero-concordant negative.

The findings of B&M are intriguing. They argue that combined effect of these sources of bias in earlier analysis of the Rakai evidence has been enormously to inflate estimates of relative acute phase – relative to chronic phase – HIV infectivity. B&M estimate the relative hazard of transmission during acute phase at 5.3, the acute phase duration at 1.7 months, and the “extra-hazard months” contributed by the acute phase (a measure adopted by the authors in order to ensure comparability of study results) at 8.4. Previous estimates give levels of increased infectivity due to acute phase which are equivalent to between 31 and 141 hazard months. If the results of B&M are confirmed in subsequent studies, the preventative gains of ART scale-up could be greater than hitherto supposed.

Achieving HPV herd immunity cost-effectively. When does it make sense to allocate resources preferentially to boys?

23 Apr, 15 | by Leslie Goode, Blogmaster

Recent empirical studies of HPV vaccination have provided evidence that marginal vaccination costs increase with coverage.  Let us take into account – they argue – not just the vaccine price, but the cost of education and outreach programmes that would be needed so as to reach the yet unvaccinated population.  If we do so, we are likely to find that raising the vaccination rate for pre-adolescent girls, let us say, from 40-41%, proves considerably more expensive than raising it from 20-21%.  This, in turn, raises the question whether – given the achievement of herd immunity is the ultimate goal – resources are necessarily best allocated when directed to the female rather than the male pre-adolescent population. Could it even be that – at certain levels of coverage and a certain rates of increase in marginal vaccination cost (for girls and for boys) – resources might be more effectively allocated to the vaccination of pre-adolescent boys? Ryser & Myers in a recent study seek to model the impact of marginal cost increase in order to answer this question.  In the case of US, at least – with rates of vaccination standing currently, for girls and boys, at, respectively 37% and 13.9% – they argue in cost benefit terms for re-directing resources to boys.  However, the question is no doubt relevant to other countries in which HPV has been introduced, but levels sufficient for herd immunity, have not yet been achieved.

Optimal allocation of new resources as between girls and boys for a given level of vaccination is indicated in the diagrams on p.40.  Marginal vaccination cost increase is estimated at a higher, a lower, and zero level.  What is striking is the radically different patterns of optimal allocation between girls and boys in those three scenarios.  At the very least, the results challenge the orthodoxy of the superior cost benefit of female vaccination. They also indicate the importance of further empirical research into marginal vaccination cost increase.

The limitations of the study are largely due to the assumption of a closed sexual network of 14-18 yr old heterosexual adolescents.  The attempt is made to factor in the impact of various complicating factors, such as the assortativity of vaccine uptake with sexual activity, the likely presence of additional relationships between females inside, and older males outside, the network, and asymmetric vaccination cost curves as between girls and boys.  But the most serious limitation was beyond the power of the study to address.  This is the restriction of the modelled network to heterosexual relations, and the exclusion from consideration of a large number of HPV-related conditions such as anal and oro-pharyngeal cancers which have higher incidence among MSM and HIV-infected individuals (Lawton & Asboe (STIs); English & Pourbohloul (STIs)).  One wonders, therefore, whether the case for male HPV vaccination is not a great deal stronger than might appear from this paper.  At all events, a case is made that, even when these conditions are excluded, a greater allocation of HPV vaccination resources to males may be justifiable – e.g. currently in the US.  For the impact of the recent extension of the HPV vaccination programme to males in Australia (the first country to have taken this step (2013)), see Korostil & Donovan (STIs).

Can financial incentives help address the problem of HIV lost-to-follow-up in the US?

21 Apr, 15 | by Leslie Goode, Blogmaster

An article by Skarbinski & Mermin, discussed in my recent blog, Skarbinski & Mermin (STI/blogs), throws into sharp light the problem of the 45.2% of the HIV/AIDS infected population who are diagnosed but lost to follow-up.  According to their estimate this group are responsible for 61.3% of transmissions.  Various local attempts have been made to address this problem through more “wrap-around” approaches to health care (Bocour & Less (STI/blog)), or through computer assisted self-interviewing (Dombrowski & Golden (STI).  Another approach is the use of financial incentives.  Relatively small-scale and local experiments in various forms of conditional cash transfer have been described by a number of studies recently featured in STIs.  These have aimed, for example, to reduce STIs and pregnancy among Latino youth in San Francisco (Minnis & Padian (STI)), to encourage HIV-infected men to bring their wives for testing in Pakistan (Khan & Khan (STI), to incentivize villagers to remain HIV-free in Lesotho (Bjoerkman-Nyqvist & Svensson (STI)), or to promote syphilis testing amongst indigenous groups in Edmonton, Canada (Gratrix & Talbot (STI)).

Yet what role could financial incentives play in the broader context of mainstream HIV management in the US?  Could they help to address the problem of retention in HIV care across the range of HIV care settings?

A recent US study, HPTN 065 (TLC-Plus) reported at the 2015 Conference on Retroviruses and Opportunistic Infections (CROI) addresses this very question.  It involved two-year RCT in a total of 37 testing sites in Bronx and Washington DC., randomized to an intervention and a control arm.  The intervention offered incentives for both linkage-to-care, and viral suppression.  For linkage-to-care, the incentive consisted in the issue to HIV diagnosed of a $25 coupon redeemable when the participant returned to have blood taken for laboratory tests, and a $100 coupon redeemable when he/she returned for test results and to discuss a long-term care plan.  For viral suppression, it took the form of the issue of a $70 gift card to patients taking medication at the end of every three months if they had an undetectable viral load.  Over the duration of the trial, 1,061 coupons were given for linkage-to-care, and 40,000 gift cards were dispensed to 9,153 patients for viral suppression.

Disappointingly, no overall increase was observed in intervention compared to control settings, either in linkage-to-care or in the proportion of patients achieving viral suppression.  However, the intervention brought significant improvements in viral suppression and continuity of care (completion of four out of five possible visits for tests in last 15 months) within certain specific care settings.  In particular, these were: care settings where <65% of the patients were achieving viral suppression at the start of the study (improvements of 10% overall, 13% as measured in the last three months of the study); small-scale care settings (improvements of 13% as measured in the last three months, and of 19% overall in continuity of care).  The investigators conclude that there may be a role for financial incentives in specific health care settings.

Indiana State ban on Needle Share programmes faces challenge of an IDU-fuelled HIV spike

20 Apr, 15 | by Leslie Goode, Blogmaster

In 2011 18.5% of HIV infections in the US were attributable to intravenous drug-use (IDU) – a significant proportion (Lansky & Wejnert (STIs)).  The issue of IDU fuelled HIV transmission has been brought forcibly to the attention of Americans in the last few weeks by the recent HIV outbreak in Scott County, Indiana, US.  This local epidemic appears to have been the result of the recreational use of the opiate, Opala. The number of infections has continued to rise, reaching a new peak of 130 this last week (Indystar/needle exchange; npr/Indiana’s HIV spike).

The effectiveness of public health interventions amongst IDU, including needle exchange programmes is well-established. Recent studies in Russia and East-European contexts (Vagaitseva & Demyanenko (STIs); Boci & Bani (STIs)), where IDU accounts for greatest proportion of infections,  have also come to very positive conclusions about their cost-effectiveness (Demyanenko & Vagaitseva (STIs).  They have also considered ways of improving uptake among drug-users (Boci & Hallkaj (STIs).  Sadly, in 23 states of the US – as in Russia and some East-European countries – traditional legal restrictions on needle exchange programmes remain in force (LawAtlas/US).  Indiana just happens to be one of these US states.  Its governor, who has had to authorize a short-term moratorium on the legal restriction of needle exchange in response to the outbreak, just happens to be Mike Pence, a republican who is known for his especially hawkish views on social issues (see “US Republicans prepared to put the poor at risk” (STI/blogs)) and favours continuation of the ban.

Needless to say, an order authorizing the temporary suspension of the restrictions on needle exchange was issued last month.  A needle-exchange programme has distributed 5,300 clean needles to drug-users since 8th April when it began its activities.

Unfortunately, however, the temporary suspension is due to expire on 25th April.  It also applies only to Scott County. Health experts are pushing legislators to allow needle exchange in neighbouring counties of Indiana, where high levels of HCV indicate a high risk of similar outbreaks.  On Monday, a joint Senate and House Legislative Committee will consider a measure, authored by Ed Clere, a representative from a neighbouring county, to authorize local public health and law enforcement authorities to work together to start their own need exchange programmes. But Governor Pence has threatened to veto the measure.  He declines to explain his position in public, but is said by Senate President, David Long, to believe that needle exchange programmes lead to greater drug use (News & Tribune/Indiana’s needle exchange bill).

Retention in care rather than diagnosis may prove the ultimate challenge for US HIV response

25 Mar, 15 | by Leslie Goode, Blogmaster

The real challenge which the US HIV/AIDS epidemic poses for the US public health services is not simply to achieve higher levels of diagnosis – but, far more than that, to improve linkage to, and retention in, care.  This claim is hardly controversial. But it is thrown into stark relief in a recent study by Skarbinski & Mermin, which estimates the number of HIV transmissions attributable to non-retention in care for 2009.

The authors employ the notion of a five-phase “care continuum”.  Using population data from the National HIV Surveillance System and medical data from the National HIV Behavioral Surveillance System and the Medical Monitoring Project, they estimate the number of HIV transmissions occurring at each phase.  The phases in the continuum are: (1) infected, but undiagnosed; (2) diagnosed, but not retained in care (attending at least one visit to a medical care provider Jan. – April 2009); (3) diagnosed, retained in care, but not given ART; (4) diagnosed, retained in care, prescribed ART, but not virally suppressed; (5) virally suppressed.

The reduction in attributable transmissions achieved for those diagnosed but not retained in care (phase 2), as compared with those who remain undiagnosed (phase 1), is 19%.  (It is probably due to a decrease in HIV-discordant unprotected sex).  But the reduction achieved for those who achieve viral suppression (phase 5), as compared with those who remain undiagnosed, is 94%.  In estimating the epidemiological impact of these reductions, we need to factor in the percentage of the infected population at each phase.  The large proportion (45.2%) of the HIV infected who are diagnosed but not retained (phase 2) explains the very high proportion of total transmissions (61.3%) attributable to this phase.  By comparison, only 30.2% are attributable to the undiagnosed (phase 1), and 2.5% to the virally suppressed (phase 5).  The low epidemiological impact of those at phases 3 and 4 is due to the relatively low proportion of those infected who remain in these phases.

The message, then, is that achieving greater success in retaining the HIV diagnosed in care may prove the key to combating the epidemic at population level.  Of course, diagnosis remains the indispensable first step.  But the potential gains of diagnosis will be only very partially experienced, so long as such a large proportion of those diagnosed are not retained in care.  Of course, improving retention in care may constitute a somewhat different – and perhaps more difficult – challenge for the US health services from diagnosis.  The specific problems of the US health system in this regard are discussed by Sherer (STI), and the characteristics of individuals “lost to follow up” by Haddow & Mercey (STI) and Lee & Gazzard (STI).  Local attempts to address these problems through a more “wrap-around” approach to health care in the US are described in my blog Bocour & Less (STI/blog) (see Bocour &  Less).  There has also been interest in the computer assisted self-interviewing in order to engage those lost to care (Dombrowski & Golden (STI)).

Reported 86% effectiveness for MSM PrEP by PROUD study makes this intervention a viable option for UK health services

25 Mar, 15 | by Leslie Goode, Blogmaster

The Conference on Retroviruses and Opportunistic Infections has recently taken place.  At that event the UK PROUD (PRe-exposure Option for reducing HIV in the UK: immediate or Deferred) study of pre-exposure prophylaxis (PrEP) for MSM reported its results, prior to publication in the coming months.  The headline figure is an astonishing 86% for the reduction of risk of infection in the intervention group.  Hitherto, results of PrEP trials, largely conducted in Africa, have often been disappointing.  This is probably on account of poor adherence (VOICE D( STI/blog); Haberer & Bangsberg (STI/blog); Hendrix & Bumpus (STI/blog)).  The good result achieved here is no doubt attributable to good adherence.  It demonstrates, as these earlier trials have not, the true effectiveness of PrEP.

The UK trial included 545 participants at 13 practices. 276 were randomized to receive PrEP immediately, while the remaining 269 received it after a year.  Earlier PrEP trials have been blind and placebo-controlled.  But this design had the advantage of demonstrating the effectiveness of PrEP in real life. The participants were aware if they were taking the active drug and could have changed their sexual behaviour accordingly.  Given one of the major concerns around PrEP is that of risk compensation – i.e. taking advantage of the protection of PrEP to engage in more risky behaviour than they would otherwise (Marcus & Grant (STI/blog); Baeten & Celum (STI/blog)) – this was a valuable aspect of the trial.

In the period to October 2014, there were 22 HIV infections – 3 in the immediate, and 19 in the deferred group.  This gives us the headline figure of 86%.  At this point, ethical considerations dictated that the study design be changed so all participants received PrEP from then on.  Initially, this study was intended to be a pilot, and to be followed by a larger scale trial.  The decisiveness of the interim findings, however, led to cancellation of that further study.  (For an interesting commentary on the need for researchers to keep pace with changing ethical parameters, see Cohen & Sugarman (STI/blog)).  Cost-effectiveness analyses are apparently underway.  No details are given in the report.  But evidently the high effectiveness observed in the study will allow investigators to present a far more positive case for PrEP than has been warranted by earlier trials (see Borquez & Hallett (STI); Gomez & Hallett (STI/blog); Cremin & Garnett (STI)).  They are also working with stakeholders on how PrEP services could be commissioned across NHS and local authorities.

The varied nature of the US HIV/AIDS epidemic: what makes the South so different?

27 Feb, 15 | by Leslie Goode, Blogmaster

As of 2011, 38% of all US citizens diagnosed with HIV were from a block of nine states in the south-east, sometimes referred to as “the South”: Louisiana, Alabama, Florida, N. and S. Carolina, Georgia, Texas, Mississippi and Tennessee. Death rates among those living with HIV in this region were, by far, the highest of any US region.  A recent study (Reif & Wilson) uses CDC HIV surveillance data to seek to assign characteristics to the large number of persons in that region diagnosed with, and frequently failing to survive, HIV/AIDS, in order to determine what it is about this region of the US that makes it peculiarly vulnerable to the epidemic.

A number of these characteristics were not specific to the South, but shared by all the southern states: the high proportion of those diagnosed who are female (27%: US average 20.9%), who have contracted HIV through hetero-sexual relations (14.5%: US average 11.7%) and who fall in the 13-24 yr age group. What differentiates the South more particularly, is the considerably higher percentages of diagnoses among those living in rural (11%) and suburban (17%) areas, though even urban rates (29.6 per 100,000) are higher in the South than in other regions.  Five-year survival following AIDS diagnosis, at 73%, is considerably lower than the US average (77%), and lower than for any other region. Survival rates following HIV diagnosis were considerably lower for rural (82%) than for urban (86%) areas.  Above all, the death, rate at 27.3 per 1000, was considerably higher than in any other region of the US. (HIV mortality in the UK fell from 21.8 to 8.2 per 1000 over the years 1997-2008 (Smith & Delpech (STI))).

The high death rates for the South suggest, the authors claim, a fundamental “disconnect” between diagnosis and maintenance of care in the region. Moreover, when the figures are adjusted to take account of characteristics of individuals living with HIV, including sex, race, mode of transmission etc., the disparity remains substantively unchanged or accentuated. This likely indicates underlying structural factors affecting the states of the South.  Obvious candidates would be lower insurance coverage, lower levels of income and education. On the basis of the convergence of high death rates and the high proportion of rural and suburban HIV cases in the region, the authors also evoke, more speculatively, the “class system unique to the US South” which has traditionally allowed little social mobility.  They argue this may have contributed towards a social environment among lower strata characterized by a combination of stigmatization and distrust of medical services, which is very unconducive to retention in care.

Trialling innovative approaches to STI partner services: Partner-Delivered vv. Accelerated Partner Therapy

26 Feb, 15 | by Leslie Goode, Blogmaster

It is vital to treat partners of patients with curable STIs as quickly as possible.  But the effectiveness of interventions to achieve this proves hard to measure – and the case for increasing resources correspondingly difficult to make.  The inadequacy of the resources available to existing partner services has led some investigators in the US and UK to seek out innovative approaches to ensuring the treatment of partners which are less expensive.  One option – Patient-Delivered Partner Therapy (PDPT) – is to provide treatment for partners via the patient and without prior medical assessment of the partner.  The problems with this are: first, that PDPT may not conform to legal (Cramer & Leichliter (STI)) or professional guidelines; second, that concomitant infections (e.g. HIV) in the partner may go undiagnosed and untreated. An alternative solution – Accelerated Partner Therapy (APT) – is to treat the partner via the patient, but only after a medical assessment conducted by telephone or with a pharmacist (Golden & Estcourt (STI); Dombrowski & Golden (STI)).

The option of PDPT has been trialled in various US clinics (Mickievicz & Rietmeijer (STI); Sanchez & Schillinger (STI); but its impact is difficult to evaluate on a local level. Now, for the first time, Golden & Holmes have attempted a population-level randomized control trial of uptake and impact across 23 out of the 25 counties of Washington State.  This impressively large-scale operation had two elements.  The first was the provision of free PDPT, and involved: 1. informing all clinicians about the programme; 2. making stocks of free PDPT available to clinicians who had reported ≥ one case of Chlamydia or Gonorrhoea, and to certain large pharmaceutical chains; 3. visiting clinicians reporting frequent cases for the purpose of educating staff about the programme.  The second element was the possibility offered to diagnosing practitioners via routine report forms of having the provision of partner services handled by the state public health department. This intervention was rolled out in four successive waves to different counties in turn, thus enabling the impact of the intervention to be controlled against the default situation in the counties of each wave.

As regards uptake, percentage of persons receiving PDPT from clinicians rose in intervention periods from 18% to 34%, and percentage receiving partner services from 25% to 45%.  This is broadly comparable with what has been achieved by more local interventions in the US.  Unfortunately, it is one thing for a pack to be accepted by the index patient, another for a partner to be successfully treated.  Hence the interest of G&S’s attempt to evaluate population-level impact – through testing in sentinel clinics in the case of Chlamydia, and through incidence of reported infection in the case of Gonorrhoea. It was undoubtedly ambitious of G&S to seek an indicator of population level impact for a comparatively brief intervention.  It is no surprise that the results are less than overwhelming. Chlamydia test positivity and gonorrhoea incidence in women declined respectively from 8.2% to 6.5% and from 59.6 to 26.4 per 100,000. The latter more impressive reduction is unfortunately hard to distinguish from a strong secular trend in the same direction in various states.

There are more general problems, however – such as knowing whether the handing over of PDPT packs is resulting in the successful treatment of disease, or whether it may even be contributing to an ongoing failure to diagnose concomitant partner infections.  These might weigh in favour of the alternative approach recently developed in UK clinics: APT.  Estcourt & Johnson (STI) report uptakes of 66% and 59% for versions of APT as against 36% for conventional PS.  Sending a treatment pack following a telephone interview would seem to offer a better guarantee of partner treatment, than offering a pack on the basis of nothing more than a stated willingness of the index patient to deliver it.  At the same time, interviewing the partner averts the risk of doing harm by pre-empting consultations at which a fuller diagnosis of the partner’s condition would have been possible.  A population-level trial of the impact of APT has yet to be undertaken.

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