Whitney P. Bowe

Validity of Subject Self-Report for Acne

Background/Objective: Acne prevalence studies often use subject self-report as data source. Our aim was to evaluate the validity of acne self-report. Methods: Responses of university students to an acne questionnaire were compared to the trained observer’s concurrent examination of acne. The validity of self-report was measured by sensitivity, specificity, positive predictive value and negative predictive value. Agreement was measured by Cohen’s kappa and correct classification percentage. Results: The sensitivity of self-report was 0.55 (95% CI 0.47–0.63), the specificity was 0.72 (95% CI 0.63–0.80), the positive predictive value was 0.70 (95% CI 0.61–0.78), and the negative predictive value was 0.57 (95% CI 0.49–0.65). Cohen’s kappa was 0.26 (95% CI 0.15–0.38) and correct classification percentage was 63. Conclusions: Validity of self-report was moderate at best and agreement was fair, indicating that college students could not accurately report that they have acne. This is likely not sufficient for clinical or research activities or to assure that individuals who self-guide their acne therapy actually have acne.

Upper Respiratory Tract Infection in Household Contacts of Acne Patients

Background: Antibiotic use in acne patients has been associated with an increased risk of upper respiratory tract infection (URTI). Methods: This was a retrospective cohort study using the General Practice Research Database of the United Kingdom. All study subjects were identified as sharing a residence with a patient with a diagnosis of acne. Outcome of interest was a URTI. Results: We identified 98,094 contacts of acne patients. A contact of an acne patient who had a URTI was about 43% more likely to develop a URTI than a contact of an acne patient who did not have a URTI (OR = 1.43 CI = 1.33–1.52, p < 0.001). Exposure to an acne patient using antibiotics did not independently increase a contact’s risk of URTI (OR = 0.94, CI = 0.89–1.00, p = 0.063). Conclusions: Although acne patients on antibiotics are about 2 times more likely to develop URTIs, their household contacts do not appear to be at an increased risk of URTI.