Interpreting patient-reported outcomes following anterior cruciate ligament tears or traumatic meniscal injuries

How do we know if our patients are getting better? From an OPTIKNEE systematic review.

This blog is part of a series on work by OPTIKNEE Consensus. This is an international consensus group focused on improving knee health and preventing osteoarthritis after a traumatic knee injury.

Keywords: patient-reported outcome measures (PROMs), anterior cruciate ligament (ACL), meniscus

Patients’ perspectives are critical for understanding if a treatment they have received has been effective e.g. is the questionnaire score, or change in score, meaningful to them? In this blog, we review how patient-reported outcome measures (PROMs) can be used to evaluate whether patients being treated for anterior cruciate ligament (ACL) tears or traumatic meniscal injuries feel that they are satisfied (or not) with their current status, or if they have experienced meaningful change. These suggestions are from one of several systematic reviews that we published as part of OPTIKNEE’s international consensus project that aims to optimize knee health and prevent post-traumatic osteoarthritis following traumatic knee injuries. 

Generally, the ‘thresholds’ used to help interpret the score on a PROM are meant to evaluate the ‘average patient’s experience’ This may have limited use when clinicians are trying to interpret the score from a PROM filled-out by a single patient. Clinicians will likely better understand their patient’s experience if they directly ask them “Are you satisfied with how you are currently doing? What do you think about your improvement?” Combining patient’s subjective answers together with the answers to individual items in the PROM questionnaire will help engage in a meaningful discussion about their treatment.

 

Why is this study important?

PROMs are used extensively in clinical settings and in research to evaluate a patient’s perception of their pain, function, quality of life, etc. after ACL tears or meniscal injuries. However, it can be difficult to interpret whether a score (or change in score) is clinically meaningful. For example, minimal important change (MIC) indicates the smallest amount of improvement (or worsening) in a PROM score that an average patient would perceive as important. Patient acceptable symptom state (PASS) indicates how high (or for ‘Treatment Failure’, how low) the score on the PROM would need to be for the average patient to feel their current status is satisfactory, or disappointing. Unfortunately, the terminology and methods used in the field of PROMs are complicated and currently there is no consensus on how to determine meaningful ‘thresholds’. We brave readers to plunge into our full paper. The bottom line is that knowing the evidence-based MIC and PASS thresholds for ACL tears and meniscal injuries. This alongside when and how to use these thresholds, can help clinicians interpret PROM scores from an individual patient.

 

How did the study go about this?

We systematically searched 5 databases for studies that calculated MIC, PASS, Treatment Failure or similar thresholds for any PROM in individuals with ACL tear or traumatic meniscal injury with a mean injury age of ≤35 years. Then we critically appraised and synthesized all the threshold estimates.

 

What did the study find?

We found 18 studies (15 ACL tear, 3 meniscal injury). We focused on ‘anchor-based MIC thresholds’ (where an anchor e.g., ‘much worse’ and ‘much better,’ is used at either end of a scale) because they are more valid than distribution-based thresholds (where the change in scores is compared to some measure of variability e.g., standard deviation). Below we report thresholds (or ranges of thresholds) that were assessed to be of either: (1) high credibility; or (2) low credibility in more than one study where scores fell within a range (< 10 points) (Table). The interested reader can see the remaining thresholds in our paper.

 

Table 1. MIC and PASS thresholds in which Credibility was rated ‘High’ or in which scores among multiple low credibility thresholds converged to within a 10-point range

PROM Threshold Credibility
ACL tears  MIC
KOOS* Quality of Life 18 High
KOOS Symptoms -1.2 to 5.4 Low
KOOS Function in Daily Living 0.5 to 8.1 Low
IKDC-SKF 7.1 to 16.2 Low
ACL tears PASS
KOOS Function in Daily Living 92 to 100 n/a^
Traumatic meniscal tears PASS
KOOS Symptoms 73 to 78 n/a^
KOOS Quality of Life 53 to 57 n/a^

*KOOS: Knee injury and Osteoarthritis Outcome Score; IKDC-SKF: International Knee Documentation Committee – Subjective Knee Form; ^No tool available to measure credibility in PASS or Treatment Failure thresholds

Key messages:

 

Authors:

Erin Macri, Alison Hoens, James Young, Adam Culvenor, Jackie Whittaker, Ewa Roos

 

Resources and references:

OPTIKNEE | Musculoskeletal Health, Sport & Exercise Lab (ubc.ca)

Macri EM, Young JJ, Ingelsrud LH, et al. Meaningful thresholds for patient-reported outcomes following interventions for anterior cruciate ligament tear or traumatic meniscus injury: a systematic review for the OPTIKNEE consensus. British Journal of Sports Medicine Published Online First: 16 August 2022. http://dx.doi.org/10.1136/bjsports-2022-105497 

Devji T, Carrasco-Labra A, Qasim A, et al. Evaluating the credibility of anchor based estimates of minimal important differences for patient reported outcomes: instrument development and reliability study. BMJ 2020;369:m1714.  https://doi.org/10.1136/bmj.m1714 

Urhausen AP, Berg B, Øiestad BE, et al. Measurement properties for muscle strength tests following anterior cruciate ligament and/or meniscus injury: What tests to use and where do we need to go? A systematic review with meta-analyses for the OPTIKNEE consensus. British Journal of Sports Medicine Published Online First: 16 September 2022. http://dx.doi.org/10.1136/bjsports-2022-105498 

Berg B, Urhausen AP, Øiestad BE, et al. What tests should be used to assess functional performance in youth and young adults following anterior cruciate ligament or meniscal injury? A systematic review of measurement properties for the OPTIKNEE consensus. British Journal of Sports Medicine Published Online First: 13 June 2022. http://dx.doi.org/10.1136/bjsports-2022-105510 

Culvenor AG, Girdwood MA, Juhl CB, et al. Rehabilitation after anterior cruciate ligament and meniscal injuries: a best-evidence synthesis of systematic reviews for the OPTIKNEE consensus. British Journal of Sports Medicine Published Online First: 29 June 2022. http://dx.doi.org/10.1136/bjsports-2022-105495 

Whittaker JL, Losciale JM, Juhl CB, et al. Risk factors for knee osteoarthritis after traumatic knee injury: a systematic review and meta-analysis of randomised controlled trials and cohort studies for the OPTIKNEE Consensus. British Journal of Sports Medicine Published Online First: 02 September 2022. http://dx.doi.org/10.1136/bjsports-2022-105496 

Filbay SR, Skou ST, Bullock GS, et al. Long-term quality of life, work limitation, physical activity, economic cost and disease burden following ACL and meniscal injury: a systematic review and meta-analysis for the OPTIKNEE consensus. British Journal of Sports Medicine Published Online First: 28 September 2022. http://dx.doi.org/10.1136/bjsports-2022-105626

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