Comment on: Risk factors for frontal fibrosing alopecia: A case-control study in a multiracial population

Frontal Fibrosing Alopecia – a review and a practical guide for clinicians

“…the consequence of a geographical selection bias [12,13]. Indeed, a multi-centre review of 355 patients conducted in Spain reported that 83% of the cases were postmenopausal women, 14% were premenopausal women, and 3% were men [2].…”

“…Firstly, observational studies have remarkably reported a high frequency of sunscreen use in subjects with FFA [15, 21,29,30,31,32]. This finding raises the question of whether sunscreen use plays a role in the disease development, which generates both interest and controversy within the medical community [13]. The link is associated particularly with facial sunscreens [15].…”

“…environmental pathogenicity in relation to this rare disease obviously requires statistical rigor in observational studies to avoid selection bias (even with matching procedures, for instance by age, gender, menopausal status and/or skin colour), recall bias for products and frequency of use, misclassification of exposure or even temporal ambiguity in questionnaires [40]. But it also requires thinking beyond this accounting-only research to prove causality, by assessing ingredient lists of hair and facial skin care products [31], by considering geographical and cultural habits [13], and by analysing the timing of events [13,40].…”

Male frontal fibrosing alopecia: study of 35 cases and association with sunscreens, facial skin and hair care products

“…4,9 In acute grade IV, cutaneous GvHD long term survival (>5 years) is only 5%. 10 We report a TEN-like acute cutaneous GvHD in a stem cell recipient, which caused a diagnostic dilemma as clinical and histopathological findings of TEN and GVHD are overlapping. As therapeutic recommendations differ between these two lifethreatening conditions, a distinction of cutaneous GvHD and TEN is very important.…”

“…Since we found no statistical difference between case and control groups in the use of facial moisturizers, sunscreens (both chemical and physical) or of other facial skin and hair care products, we disapprove the recommendation of others 9 to refrain from the use of sunscreens in FFA with credulous reference to the original unconfirmed association studies in FFA. 1,2 Finally, it is necessary to encourage alternative leads for future investigations into FFA beyond simple statistics, 10 to include a well-founded hypothesis with regard to putative causal relationships, and ultimately evidence of causality, such as timing of events, patient reaction to removal of the suspected agent and patient reaction to rechallenge. 'One of the first things taught in introductory statistics textbooks is that correlation is not causation.…”