Efficacy and safety of methylcobalamin, alpha lipoic acid and pregabalin combination versus pregabalin monotherapy in improving pain and nerve conduction velocity in type 2 diabetes associated impaired peripheral neuropathic condition. [MAINTAIN]: Results of a pilot study.

Sir,

This is in response to the comments on published article entitled, “Efficacy and safety of methylcobalamin, alpha lipoic acid and pregabalin combination versus pregabalin monotherapy in improving pain and nerve conduction velocity in type 2 diabetes associated impaired peripheral neuropathic condition. [MAINTAIN]: Results of a pilot study” published in Annals of Indian Academy of Neurology (Ann Indian Acad Neurol 2014;17:19-24).[1]

We really appreciate detailed review, analysis, and comments on the study procedure by the author in a letter to editor. We wish to clarify the details on issues raised:

No treatment or placebo-control treatments are two different subtypes of concurrently control group. Control groups used in the clinical trials can be classified into two main types: Concurrent control or historical control.[2]

Concurrent control: In this type, the control group and test groups are selected from the same population and treatment is given concurrently. Four different subtypes of control groups can be used in concurrently controlled types: placebo control, no treatment, different dose or regimen of the study treatment, or a different active treatment.

External (historical) control: In this type, the control group is the group of patients treated earlier (historical) control or patients treated during the same time period but in another setting.

In our study, the control arm was from the first category i.e., concurrently controlled (different active treatment).

We agree about the practical difficulty of conducting randomization, precautions to be taken in randomization procedure and allocation concealment to avoid bias. Both of these procedures were followed in our “Pilot” study. A total of 30 patients were randomly assigned (1:1) to two treatment groups. The patients were treated based on a pre-determined computer-generated randomization code which were prepared by a person other than investigator and were provided to the investigator in a sealed envelope separately for each patient to ensure allocation concealment. The approach of dividing alternating subjects between one group and the other was not used in the study.