Designing pain research from the patient's perspective: what trial end points are important to patients with chronic...

The goals of this study were to define the endpoints of pain research that are important to patients with chronic pain and to identify clinical and demographic variables that are associated with patients' choices of endpoints.

Interviews were completed with 40 patients seen at the anesthesia pain clinic of an urban tertiary care medical center.

Each patient was presented with 4 brief (3-4 sentences) fixed information vignettes describing studies in which new medications would be evaluated. For each, patients were asked to describe how the medication being studied might offer an improvement over their current therapy.

Measures included structured qualitative analysis of responses, the Brief Pain Inventory, and Global Distress Index of the Memorial Symptom Assessment Scale.

Patients described a total of 20 endpoints. Individually, patients cited between 2 and 9 endpoints each (mean 4.9, standard deviation 1.7). Of these, the most commonly cited were decrease pain, decrease opioid dose, decrease frequency of scheduled dose, increased ability to function, decrease frequency of breakthrough dose, and improve sleep. Patients with severe pain cited more endpoints than did those with mild or moderate pain (mean 5.5 vs. 4.3; Rank sum test p = 0.01).

These data suggest that empirical research can provide data to guide the choice of endpoints in clinical studies of pain interventions.