Background The smallest worthwhile effect (SWE) is the minimum benefit required in addition to that from a comparator, for an intervention to be considered worthwhile by patients. We aimed to estimate the SWE for rotator cuff repair (with decompression and debridement) compared to either decompression and debridement alone or to non-surgical treatment for people with atraumatic shoulder pain.

Methods Benefit-harm trade-off study. We recruited English speaking adults aged 45-75 years with shoulder pain of intensity ≥4 (on a 0-10 scale) for ≥6 months to our online survey through paid advertising on Facebook. Participants must have sought care in the past 6-months and could not have had recent shoulder surgery or significant recent shoulder trauma. Participants were explained three treatments: rotator cuff repair (with subacromial decompression and debridement), subacromial decompression and debridement alone and non-surgical treatment. Participants completed the benefit-harm trade-off survey to determine the SWE of improvements in pain and function for rotator cuff repair compared to the other treatments and again after one week to assess reliability. We used univariable linear regression to estimate associations between baseline characteristics and SWE.

Results We recruited 56 participants. The mean ± standard deviation age was 58.4±6.7 years and 39 (70%) were female. For rotator cuff repair to be worthwhile compared to decompression and debridement alone participants needed to see at least a median 40% (interquartile range (IQR) 20-62.5) between-group improvement in pain and function.

Compared to non-surgical treatment, the SWE was a median 40% (IQR 30-60). On the Western Ontario Rotator Cuff (WORC) Index the SWE values equate to a between-group improvement of 28/100 points (533/2100 on the raw WORC score). Female sex was associated with larger SWEs for both comparisons. Reliability analyses were underpowered, 25/56(45%) provided follow-up data; the intraclass correlation coefficient estimates ranged from 0.60-0.77.

Conclusions This SWE indicates the benefit required by people with shoulder pain to consider the costs and risks of surgical rotator cuff repair worthwhile is larger than previously estimated minimum clinically important differences (13.5-28/100 on the WORC Index). This SWE may be used to inform the design or interpret the findings of trials of these comparisons.

IAH, RP, RB, MLF are investigators on the Australian Rotator Cuff Trial. All other authors report no conflicts of interest.

HJH was supported by an Australian NHMRC Postgraduate Scholarship and a PhD Top-Up Scholarship from Neuroscience Research Australia and was a Neuroscience Research Australia PhD Pearl sponsored by Mrs Sandra Salteri. JRZ was supported by NHMRC Investigator Grant (APP1194105). RB was supported by an NHMRC Investigator Grant (APP1194483). MLF is supported by an NHMRC Investigator Grant Leadership 1 and provided consulting advice on the scientific advisory board for Novartis.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

University of New South Wales Human Research Ethics Committee (HC230374)

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Funding Sources HJH was supported by an Australian NHMRC Postgraduate Scholarship and a PhD Top-Up Scholarship from Neuroscience Research Australia and was a Neuroscience Research Australia PhD Pearl sponsored by Mrs Sandra Salteri. JRZ was supported by NHMRC Investigator Grant (APP1194105). RB was supported by an NHMRC Investigator Grant (APP1194483). MLF is supported by an NHMRC Investigator Grant Leadership 1 and provided consulting advice on the scientific advisory board for Novartis.

Declarations of interest IAH, RP, RB, MLF are investigators on the Australian Rotator Cuff Trial. All other authors report no conflicts of interest.

Data sharing All data and code will be shared publicly on OSF upon publication (osf.io/crj9p).

The survey codebook is available on OSF (osf.io/crj9p) All de-identified data and code used for the analysis will be made available upon publication on OSF

https://osf.io/crj9p