Recombinant human nerve growth factor in the treatment of diabetic polyneuropathy

To the Editor: The article by Apfel et al. concerning recombinant human nerve growth factor (rhNGF) in the treatment of diabetic polyneuropathy (DPN) highlights the dilemma facing many clinical trials dealing with degenerative neurologic disease.1 Although rhNGF may have some beneficial therapeutic effect in DPN, rhNGF has little chance of gaining sustained widespread clinical acceptance if the beneficial effect can only be demonstrated by various combinations of multiple endpoints that are individually, not statistically or clinically, significant. Patients and treating physicians need to “see” the benefit. Indeed, the clinical utility of some of the endpoints are vague. For example, one endpoint in this rhNGF clinical trial was the Neuropathy Impairment Lower Limbs (NISLL) score.1 The NISLL score is compiled from the grading of strength, sensation, and reflexes; the obtained score is then “normalized, in the mind of the examiner, for site, age, gender, height, weight, and physical fitness.”2 What does a NISLL score obtained in such a manner from the “mind of the examiner” actually signify? As the authors …