The prognostic importance of detecting mild sensory impairment in leprosy: a randomized controlled trial (TRIPOD 2)

This study was designed to investigate whether leprosy patients diagnosed with mild sensory impairment have a better prognosis when treated with steroids than similarly impaired patients treated with placebo. A multi-centre, randomized, double-blind, placebo-controlled trial was conducted in Nepal and Bangladesh. Patients were eligible if they had a confirmed leprosy diagnosis, were between 15 and 50 years old, had mild sensory impairment of the ulnar or posterior tibial nerve of less than 6 months duration and did not require steroids for other reasons. ‘Mild impairment’ was defined as ‘impaired on the Semmes-Weinstein monofilament test, but testing normal on the ballpen sensory test’. Subjects were randomized to either prednisolone treatment starting at 40 mg per day, tapering over 4 months, or placebo. Nerve function was monitored monthly. Any patient who deteriorated was taken out of the trial and was put on full-dose steroid treatment. Outcome assessment was done at 4, 6, 9 and 12 months from the start of the treatment. Outcome measures were the proportion of patients needing full-dose prednisolone and the Semmes-Weinstein sum scores. Each patient contributed only one nerve to the analysis. Seventy-five patients had nerves eligible for analysis, of whom 41 (55%) and 34 (45%) were allocated to the prednisolone and placebo arms, respectively. At 4 months, three patients in the prednisolone arm (7%) and six in the placebo arm (18%) had an outcome event requiring full dose steroids. At 12 months, these proportions had almost reversed, 11 (27%) and 6 (18%) in the treatment and placebo arms, respectively. In the latter group, 75% had recovered spontaneously after 12 months. Prednisolone treatment of sensory impairment of the ulnar and posterior tibial nerves detectable with the monofilament test, but not with the ballpen test, did not improve the long-term outcome in terms of recovery of touch sensibility, not did it reduce the risk of leprosy reactions or nerve function impairment beyond the initial 4-month treatment phase. Two unexpected main findings were the strong tendency of mild sensory impairment to recover spontaneously and the fact that patients with mild sensory impairment without any other signs or symptoms of reaction or nerve function impairment are relatively rare.