Generalizing from a controlled trial: the effects of patient preference versus randomization on the outcome of inpatient versus outpatient chronic pain management

Patients accepting randomization in a randomized controlled trial (RCT) may not be representative of the clinical population from which they are drawn , calling into question the generalizability of study findings. Comparison of randomized and non-randomized inpatient and outpatient samples at baseli ne and in treatment outcomes up to one year was made to determine whether t he findings of the RCT generalized to non-randomized patients in the same t reatment program. One hundred and twenty one patients with intractable pain , randomized between inpatient, outpatient and waiting list control, were c ompared with 128 who elected for either inpatient or outpatient treatment. Treatment was a group-based multidisciplinary cognitive-behavioral treatmen t program aimed at enabling patients to return to more normal function desp ite persistent pain, delivered to mixed groups of randomized and elective p atients, and outcome was measured by physical performance, pain impact on f unction, mood, and drug use. Agreement to randomization was a function of t ravelling distance from home to hospital. Nonrandomized patients largely re sembled their randomized counterparts before and after treatment. In order to indicate the clinical significance of results, analyses were conducted u sing numbers needed to treat (NNTs). NNTs estimate the number of patients r equired in the treatment condition for one of them to achieve the specified outcome who would not have achieved it in the comparison condition. Across a range of measures at one month follow-up, comparison of inpatients with outpatients gave NNTs between 2.3 and 7.5, and comparison of inpatients wit h waiting list controls gave NNTs between 2.3 and 3.6, At one year inpatien ts showed greater likelihood than outpatients of maintaining these treatmen t gains. (C) 1999 International Association for the Study of Pain. Publishe d by Elsevier Science B.V.