Applicability of Proposed Diagnostic Criteria of Pityriasis Rosea: Results of a Prospective Case-Control Study in India

BACKGROUND: The diagnosis of pityriasis rosea (PR) is generally clinical. Previous studies usually recruited relatively small numbers of patients and control subjects, leading to low power of study results. Systematic reviews and meta-analyses cannot be readily performed, as the inclusion and exclusion criteria of these studies were not uniform. We have previously validated a set of diagnostic criteria (DC) in Chinese patients with PR. AIM: Our aim is to evaluate the validity and applicability of the DC of PR in Indian patients with PR. STUDY DESIGN: Prospective unblinded pair-matched case-control study. MATERIALS AND METHODS: The setting is a dermatology clinic in India served by one board-certified dermatologist. We recruited all 88 patients seen by us during five years diagnosed to have PR to join our study. For each study subject, we recruited the next patient who consulted us with differential diagnoses of PR as control subjects. We applied the DC of PR on all study and control subjects. RESULT: The sensitivity, specificity, positive predictive value, and negative predictive value of the DC were all 100%. Two-tailed Fisher's exact probability test result was 0.036. Φ was 1.00. CONCLUSION: The set of DC can be validly applied to Indian patients with PR.