Reasons for Not Enrolling in a Randomized Clinical Trial and Patient Preferences for Knee Osteoarthritis Treatment.

Research Purpose: Low enrollment in randomized control trials (RCTs) poses a threat to external validity. We conducted a secondary analysis to identify factors associated with patients' decisions to enroll in an RCT of knee osteoarthritis (KOA) treatments (injection, physical therapy, or combination). We assessed the extent to which demographic characteristics, treatment preferences, and history varied by patients' decisions to enroll. Among those who declined, we examined patterns in their treatment decisions. Major Findings: Among those who declined (n = 124), treatment history was associated with treatment decisions. Patients receiving injections had the highest BMI, patients receiving PT had the highest proportion of prior surgery, and treatment naïve patients had the highest proportion of PT referrals. Reasons for declining enrollment included strong treatment preference, unwillingness to be randomized, and logistics. Treatment preferences and treatment history appear to be associated with RCT enrollment. Conclusions: Findings from our secondary analysis could inform future KOA research by encouraging researchers to consider treatment preferences and randomization tolerance. We make suggestions for improvement of study enrollment, such as patient advocacy.