Risk Factors for Loss to Follow-up in 3202 Patients at 2 Years After Anterior Cruciate Ligament Reconstruction: Implications for Identifying Health Disparities in the MOON Prospective Cohort Study.

Background: Understanding the risk factors for loss to follow-up in prospective clinical studies may allow for a targeted approach to minimizing follow-up bias and improving the generalizability of conclusions in anterior cruciate ligament reconstruction (ACLR) and other sports-related interventions.

Purpose: To identify independent risk factors associated with failure to complete (ie, loss to follow-up) patient-reported outcome measures (PROMs) at 2 years after ACLR within a well-funded prospective longitudinal cohort.

Study Design: Cohort study (prognosis); Level of evidence, 2.

Methods: All patients undergoing primary or revision ACLR enrolled in the prospectively collected database of the multicenter consortium between 2002 and 2008 were included. Multivariate regression analyses were conducted to determine which baseline risk factors were significantly associated with loss to follow-up at a minimum of 2 years after surgery. Predictors assessed for loss to follow-up were as follows: consortium site, sex, race, marital status, smoking status, phone number provided (home or cell), email address provided (primary or secondary), years of school completed, average hours worked per week, working status (full-time, part-time, homemaker, retired, student, or disabled), number of people living at home, and preoperative PROMs (Knee injury and Osteoarthritis Outcome Score, Marx Activity Rating Scale, and International Knee Documentation Committee).

Results: A total of 3202 patients who underwent ACLR were enrolled. The 2-year PROM follow-up rate for this cohort was 88% (2821 of 3202). Multivariate analyses showed that patient sex (male: odds ratio [OR], 1.80) and race (black: OR, 3.64; other nonwhite: OR, 1.81) were independent predictors of 2-year loss to follow-up of PROMs. Education level was a nonconfounder.

Conclusion: While education level did not predict loss to follow-up, patients who are male and nonwhite are at increased risk of loss to follow-up of PROM at 2 years. Capturing patient outcomes with minimal loss depends on equitable, not equal, opportunity to maximize generalizability and mitigate potential population-level health disparities.

Registration: NCT00478894 (ClinicalTrials.gov identifier).