Population characteristics, symptoms, and risk factors of idiopathic chilblains: a systematic review, meta-analysis, and meta-regression.

Chilblains or perniosis is a non-freezing cold injury causing painful inflammatory skin lesions. Its pathogenesis remains poorly understood, notably because it is often studied as secondary to other underlying conditions. To systematically investigate the population characteristics, symptoms, and predisposing factors of chilblains, in otherwise healthy adults who are exposed to cool/cold environments. We screened PubMed, Embase, and Cochrane Library for studies of chilblains published from inception to February 12, 2021. Randomized trials, intervention studies, cohort studies, case-control studies, epidemiologic assessments, other observational studies, surveys, and studies of screening and diagnostic tests incorporating ≥1 groups of adult patients with a final diagnosis of chilblains.

We adopted the PRISMA reporting guidelines (PROSPERO: CRD42021245307). Risk of bias was assessed by two independent reviewers using the RTI item bank. We used GRADE analysis to assess quality of the evidence in the meta-analyses outcomes. Random-effects model meta-analyses were performed to calculate the pooled prevalence of histopathological features. Mixed-effects meta-regressions were used to assess other sources of between-study heterogeneity.

Thirteen studies involving 477 patients with an average age of 34 years were included. Chilblains affects more women than men, up to 22.5% of the body skin surface; most frequently the hands, fingers, feet, and toes. The most frequent clinical symptoms are papules, nodules, and itching. Meta-analyses of nine studies with 303 patients showed that they are very likely to test positive in four histopathological features: perivascular lymphocytic infiltrate (81%), basal vacuolation (67%), papillary dermal edema (66%), and perieccrine lymphocytic infiltrate (57%) (I2: 0%; certainty: high). Meta-regressions (all p≤0.05) showed that outdoor work and physically strenuous occupations increase the percent of body surface area being affected by chilblains, and that smoking and frequent occupational exposure to water increase the prevalence of histopathological features.

The population characteristics, symptoms, and predisposing factors of chilblains revealed in this analysis should be incorporated in medical care to improve the condition’s diagnosis and management.