Association of Rosacea With Risk for Glioma in a Danish Nationwide Cohort Study

IMPORTANCE Rosacea, a common facial skin disorder, has a poorly understood pathogenesis in which increased matrix metalloproteinase activity might play an important role. Glioma accounts for 80% of all primary malignant tumors in the central nervous system, and these tumors also show upregulation of certain matrix metalloproteinases. OBJECTIVE To investigate the association between rosacea and the risk for glioma. DESIGN, SETTING, AND PARTICIPANTS Nationwide cohort study of the Danish population from individual-level linkage of administrative registers. All Danish citizens 18 years or older from January 1, 1997, to December 31, 2011, were eligible for inclusion. A total of 5 484 910 individuals were eligible for analysis; of these, 68 372 had rosacea and 5 416 538 constituted the reference population. Data were analyzed from July 14 to August 10, 2015. MAIN OUTCOMES AND MEASURES The outcome of interest was a diagnosis of glioma. Incidence rates per 10 000 person-years were calculated, and incidence rate ratios adjusted for age, sex, and socioeconomic status were estimated by Poisson regression distribution models. RESULTS Of the 5 484 910 individuals in the study population, 21 118 individuals developed glioma during the study period, including 20 934 of the 5 416 538 individuals in the reference population (50.4% women; mean [SD] age, 40.8 [19.7] years) and 184 of the 68 372 patients with rosacea (67.3% women; mean [SD] age, 42.2 [16.5] years). The incidence rate (95% CI) of glioma was 3.34 (3.30-3.39) in the reference population and 4.99 (4.32-5.76) in patients with rosacea. The adjusted incidence rate ratio (95% CI) of glioma in patients with rosacea was 1.36 (1.18-1.58) in our primary analysis. When analyses were limited to patients with a primary diagnosis of rosacea by a hospital dermatologist (n = 5964), the adjusted incidence rate ratio was 1.82 (1.16-2.86). CONCLUSIONS AND RELEVANCE Rosacea was associated with a significantly increased risk for glioma in a nationwide cohort. This association may be mediated, in part, by mechanisms dependent on matrix metalloproteinases. Increased focus on neurologic symptoms in patients with rosacea may be warranted.