Survey mode influence on patient-reported outcome scores in orthopaedic surgery: telephone results may be positively biased


Purpose: Patient-reported outcome (PRO) scores are used to evaluate treatment modalities in orthopaedic surgery. The method of PRO collection may introduce bias to reported surgical outcomes due to the presence of an interviewer. This study evaluates post-operative PROs for variation of outcomes between survey methods-in-person, online, or telephone.

Methods: From 2008 to 2011, 456 patients underwent arthroscopic surgical treatment for acetabular labral tears. All pre-operative surveys were completed in the clinic during pre-operative visit. Two-year follow-up questionnaires were completed by 385 (84 %) patients. The PRO data were prospectively collected pre- and post-operatively using five tools: modified Harris Hip Score (mHHS), Hip Outcome Score Activities of Daily Living (HOS-ADLS), Hip Outcome Score Sports-Specific Subscale (HOS-SSS), Non-Arthritic Hip Score (NAHS), and visual analog scale. Patients were grouped according to method of 2-year follow-up: in-person during follow-up visit (102 patients, 26 %), online by email prompt (138 patients, 36 %), or telephone with an interviewer (145 patients, 38 %).

Results: Pre-operative baseline PRO scores demonstrated no statistically significant difference between groups for mHHS, HOS-ADLS, HOS-SSS, and NAHS. Two-year post-operative PRO scores obtained by telephone were statistically greater than scores obtained in-person or online for mHHS (p < 0.001), HOS-ADLS (p < 0.001), and HOS-SSS (p < 0.01).

Conclusion: This study demonstrates higher patient-reported outcome scores and greater improvement by telephone surveys compared to in-person or online. The variation of results between collection methods is indicative of a confounding variable. Clinically, it is important to understand these confounding variables in order to assess patient responses and guide treatment.

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