Design, recruitment outcomes, and sample characteristics of the Strategies for Prescribing Analgesics Comparative Effectiveness (SPACE) trial

This manuscript describes the study protocol, recruitment outcomes, and baseline participant characteristics for the Strategies for Prescribing Analgesics Comparative Effectiveness (SPACE) trial. SPACE is a pragmatic randomized comparative effectiveness trial conducted in multiple VA primary care clinics within one VA health care system. The objective was to compare benefits and harms of opioid therapy versus non-opioid medication therapy over 12 months among patients with moderate-to-severe chronic back pain or hip/knee osteoarthritis pain despite analgesic therapy; patients already receiving regular opioid therapy were excluded. Key design features include comparing two clinically-relevant medication interventions, pragmatic eligibility criteria, and flexible treat-to-target interventions. Screening, recruitment and study enrollment were conducted over 31 months. A total of 4491 patients were contacted for eligibility screening; 53.1% were ineligible, 41.0% refused, and 5.9% enrolled. The most common reasons for ineligibility were not meeting pain location and severity criteria. The most common study-specific reasons for refusal were preference for no opioid use and preference for no pain medications. Of 265 enrolled patients, 25 withdrew before randomization. Of 240 randomized patients, 87.9% were male, 84.1% were white, and age range was 21–80 years. Past-year mental health diagnoses were 28.3% depression, 17% anxiety, 9.4% PTSD, 7.9% alcohol use disorder, and 2.6% drug use disorder. In conclusion, although recruitment for this trial was challenging, characteristics of enrolled participants suggest we were successful in recruiting patients similar to those prescribed opioid therapy in usual care.