Detecting changes in patient treatment satisfaction with medicines: the SATMED-Q

The Treatment Satisfaction with Medicines Questionnaire (SATMED-Q) has shown appropriate psychometric properties exploring patients' satisfaction with treatment. Responsiveness (sensitivity to change) and known-group validity, however, still remained unknown. Thus, the goal of this study was to explore such psychometric properties for the SATMED-Q.

We used data from a 6-month prospective study carried out in pain clinics, which included patients with chronic refractory pain of neuropathic origin who needed a change in their therapies. Sensitivity to change was assessed by comparing changes in the total and domain scores between baseline and end-of-trial visits according to patients' response criterion: pain reduction 50% or more (responder). Also, correlations between changes in pain intensity and satisfaction scores were computed. Known-groups validity was explored by comparing the degree of satisfaction between groups of different levels of pain.

The sample was formed with 728 subjects (57.8 years, 61.0% women). After changing their therapy, 47% of the patients were considered responders, and pain intensity was reduced by an average of 42.9%±32.4% (P<0.001), which was significantly correlated (r =-0.524, P<0.001) with total treatment satisfaction improvement. The total score in the SATMED-Q was significantly higher in responders than in nonresponders: 80.9 (79.6-82.3) versus 66.5 (65.0-98.0) (P<0.001). Also, the instrument showed different scores of satisfaction according to different degrees of pain (mild, moderate, severe), F = 116.8 (P<0.001) in the total composite score and domains.

The SATMED-Q was sensitive to changes in patients' satisfaction with treatment. In addition, patients' different heath statuses are correlated with different levels of satisfaction with treatment.