Incidence of and risk factors for HIV-associated distal sensory polyneuropathy

To the Editor:

We read with interest the article by Schifitto et al.1 that noted a 36% 1-year incidence rate of symptomatic distal sensory polyneuropathy (SDSP) in a pre-highly active antiretroviral therapy cohort. Conclusions reached by the authors were that dideoxynucleoside (ddN) drug usage and the presence of asymptomatic DSP (ADSP) were not significant risk factors for SDSP. However, we are concerned that the study was not adequately designed to accurately assess these putative risk factors, for the following reasons:

1. It is known from previous studies that the timing of onset of toxic neuropathy after ddN initiation is short, ranging from 1 week to 6 months depending on the ddN agent and the dose administered.2 Thus we found it surprising that in order to evaluate whether ddN use was a risk factor for SDSP development, the authors studied the association between ddN use at baseline prior to entering the study and the time to development of SDSP within a subsequent 30-month period of follow-up. Even more inexplicable was the fact that patients who had discontinued taking ddN up to 6 months before cohort entry were still included in the ddN group. It would have been far more appropriate to investigate whether patients who actually took ddN drugs over the period of follow-up developed …