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  andomized 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  ontrolled 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.