The clinical effect of clomipramine in chronic idiopathic pain disorder revisited using the Spielberger State Anxiety Symptom Scale (SSASS) as outcome scale

Abstract 

Background

We have re-analysed our previous double-blind, placebo-controlled clomipramine study, changing the focus from depression to anxiety both in the response analysis and in the classification of minor affective states.

Methods

The Spielberger State Anxiety Symptom Scale (SSASS) including only the negatively phrased items was used to measure the pure anxiolytic effect. The analgesic effect was measured by the Visual Analogue Scale (VAS) for bodily pain. The General Health Questionnaire (GHQ-12) was used to identify minor affective states.

Results

In total 171 patients with chronic non-malignant pain were included (87 patients received placebo and 84 clomipramine). On the SSASS, clomipramine's (mean dose 125 mg daily) advantage over placebo in the planned 6-weeks' treatment period for all patients (intention-to-treat analysis) showed an effect size of 0.37. For completers only, the effect size was 0.45. In total 76 patients were GHQ-12 positive, and the effect size in favour of clomipramine was 0.50 (intention-to-treat approach) and 0.66 for completers. In general, the effect on the Bodily Pain VAS, i.e. the analgesic outcome, was low. Thus, even in completers who were GHQ-12 positive, the effect size was below 0.40.

Limitations

No attempt has been made to measure the degree of pure neuropathic pain in the patients.

Conclusions

In patients with chronic non-malignant pain, clomipramine is superior to placebo as regards anxiolytic effect measured by Spielberger State Anxiety Symptom Scale (SSASS). No pure analgesic effect was demonstrated.

Keywords: Chronic pain, Clomipramine, Effect size, Anti-anxiety effect, Spielberger State Anxiety Scale, General Health Questionnaire