We recently read with interest the article “Case-Control Analysis of Cochlear Implant Performance in Elderly Patients” by Friedland et al.1 It is our opinion that, despite the title, the study did not use a case-control design because of the longitudinal aspect of the study. Also, patients were not selected according to the outcome of interest, as is the procedure for a case-control study; instead, patients were selected with respect to age, a possible exposure category. The selection criteria suggest that the study actually used a cohort study design, with one-half of the analysis a basic cohort analysis and the other half a matched cohort analysis, with patients matched on duration of deafness and preimplantation Hearing in Noise Test–Quiet (HINT-Q) score.
Vogtmann E, Prentice H, Griffin R, Mishra S, McGwin G. Longitudinal Aspect of Case-Control Analysis. Arch Otolaryngol Head Neck Surg. 2010;136(11):1150. doi:10.1001/archoto.2010.176