Hospitalization for Pemphigus Associated With Climate, Pollution

Exposure to increased temperature, ultraviolet exposure, and small particle air pollution is associated with a greater rate of hospitalization among people with pemphigus, according to study results published in Clinical and Experimental Dermatology.

Investigators conducted an analysis of data from the 2002 to 2012 National Inpatient Sample provided by the US Healthcare Cost and Utilization Project. A total of 68,476,920 patients were included; among these, there were 1185 and 5179 unweighted admissions with a primary and secondary diagnosis, respectively, of pemphigus, and 5647 and 24,681 weighted admissions, respectively. Patients with a secondary diagnosis of pemphigus (mean age, 71.0±0.3 years) were significantly older than those with a primary diagnosis of pemphigus (57.8±1.0 years) and those without a pemphigus diagnosis (57.20±0.2 years).

Among inpatients with a primary diagnosis of pemphigus, 42.2% were men and 45.1% were white, with the prevalence of the disease varying significantly according to race (P <.001). Higher rates of hospitalization primarily for pemphigus were reported in the summer and fall months (ie, June-November), with the highest admission rates occurring in July and October (19.7 per million for both months). Adults hospitalized with a primary diagnosis of pemphigus had a significantly higher rate of any skin infection compared with those without pemphigus (18.9% vs 4.3%; P <.001).

Hospitalization rates for pemphigus were higher in the northeastern and western parts of the United States than in the southern and Midwestern regions. In fact, inpatients with a pemphigus diagnosis were more likely to be living in the Northeast (odds ratio [OR], 1.88; 95% CI, 1.35-2.62) and in the West (OR 2.01; 95% CI, 1.51-2.66) than in the Midwest.

Hospital admission for a primary diagnosis of pemphigus vs other diagnoses was associated with significantly lower humidity rates (mean, 64.8% vs 66.4%; P <.01), as well as significantly higher temperatures (58.7°F vs 56.3°F; P =.001), ultraviolet indices (6.0 vs 5.7; P =.02), levels of particulate matter ≤2.5 mg/m³ (12.9 vs 11.8 mg/ m³; P <.001), and levels of particulate matter ≤10 mg/m³ (26.2 vs 23.1 mg/m³; P <.001).

The investigators concluded that rising temperatures, ultraviolet exposure, and small-particle air pollution are all linked to increased hospital admissions for pemphigus, suggesting that patients with the disease may benefit from avoidance of these environmental triggers. Additional studies are warranted to confirm these conclusions and to further comprehend the mechanisms and clinical relevance of these associations.

Reference

Ren Z, Hsu D, Brieva J, Silverberg JI. Association between climate, pollution and hospitalization for pemphigus in the USA [published online June 1, 2018]. Clin Exp Dermatol. doi: 10.1111/ced.13650