Predictors of missed research appointments in a randomized placebo-controlled trial.

BACKGROUND: The primary aim of this study was to determine predictors of missed research appointments in a prospective randomized placebo injection-controlled trial with evaluations 1 to 3 and 5 to 8 months after enrollment. METHODS: This study represents a secondary use of data from 104 patients that were enrolled in a prospective randomized controlled trial of dexamethasone versus lidocaine (placebo) injection for various diagnoses. Patients were enrolled between June 2003 and February 2008. Sixty-three patients (61%) had lateral epicondylosis, 17 patients (16%) had trapeziometacarpal arthrosis, and 24 patients (23%) had de Quervain syndrome. Each patient completed a set of questionnaires at time of enrollment. Bivariable and multivariable analyses were used to determine factors associated with missed research appointments. RESULTS: Fourteen patients (13%) did not return for the first follow-up and 33 patients (32%) did not return for the second follow-up. The best multivariable logistic regression model for missing the first research visit explained 35% of the variability and included younger age, belief that health can be controlled, and no college education. The best model for missing the second research visit explained 17% of the variability and included greater pain intensity, less personal responsibility for health, and diagnosis (trapeziometacarpal arthrosis and de Quervain syndrome). CONCLUSIONS: Younger patients with no college education, who believe their health can be controlled, are more likely to miss a research appointment when enrolled in a randomized placebo injection-controlled trial.