Exploring sex differences in generalized pustular psoriasis hospitalizations.

Abstract

Generalized pustular psoriasis (GPP) is a rare subtype of psoriasis characterized by the formation of painful pustules alongside widespread inflammation.1 We sought to explore demographic differences in GPP hospitalizations using a national database of hospital encounters. We analysed the National Inpatient Sample (NIS) from 2016 to 2020. The NIS represents a stratified sample of approximately 20% of all inpatient hospitalizations across the United States. The NIS is a publicly available and de-identified database; therefore, institutional board review was not required. Diagnosis of GPP was identified by searching for International Classifications of Disease, 10th Edition (ICD-10-CM) code L40.1 as a primary diagnosis. Within this group, we collected demographic characteristics such as age, sex, race, quartile classification of the estimated median household income of residents in the patient's ZIP Code, insurance status, hospital census region and urban–rural code. Hospitals in counties with a population of <50 000 were classified as rural. Cost of care and length of stay for each hospital encounter were also collected. Patients under the age of 18 were excluded. The sample was separated into cohorts by sex. Univariate analysis was conducted using Wilcoxon rank-sum test for complex survey samples and chi-squared test with Rao & Scott's second-order correction. A total of 860 patients were identified with a primary diagnosis of GPP. The collected sample was predominantly female (64%), white (57.1%), and Medicare recipients (36.6%). Among males with GPP, the most common age group to be hospitalized was between 40 and 59 years of age whereas, the most common age group to be hospitalized among females was ages over 60 years. Notably, 27.3% of individuals in the female cohort were Black compared to 11.5% of individuals in the male cohort. Our univariate analysis approached but did not reach statistical significance when comparing race of GPP hospitalizations between the male and female cohorts (p = 0.056). The geographical distribution of GPP hospitalizations was significantly different between the male and female cohorts (p = 0.031). While the geographical distribution of male GPP hospitalizations was fairly uniform, female GPP hospitalizations were higher in the South U.S. census region (42.7%). The majority of hospitalizations took place in urban hospitals with no significant difference between male and female cohorts. The average length of stay for males was 4.9 days compared to 6.3 days for females. Cost of care (p = 0.8), median income (p = 0.3) and health insurance status (p = 0.7) were similar between the cohorts (Table 1). Our report provides an overview of patient demographics and geographical characteristics in GPP hospitalizations using a nationally representative sample between 2016 and 2020. The proportion of Medicare recipients was similar to the amount cited in prior studies evaluating the general inpatient population.2 Consistent with a prior study, our data on demographic information suggest that there is a female preponderance among patients with GPP.3 In addition, our study highlights regional differences among GPP hospitalizations, with which a majority of female patients with GPP were hospitalized in the southern region of the United States. Underlying genetic factors may play a role in the increased frequency of GPP among female patients. One study found that the majority of GPP patients presenting with AP1S3 mutations were female, suggesting that the penetrance of these mutations may be modified by sex-specific factors such as X-linked modifiers or hormonal components.4 Females may also have an earlier age of onset of GPP compared to males based on genetic differences; however, this was not assessed in our study.4 There are several limitations to our study that must be considered. Hospitalizations were identified using the ICD-10-CM code L40.1, which has not yet been fully validated for identifying GPP in an inpatient setting. As such, we may not have fully captured all patients who were hospitalized for GPP. In addition, the cross-sectional nature of this study prevents us from assessing severity of illness. However, our findings call for future research to investigate the underlying genetic and environmental factors that drive the prevalence of sex and geographical differences among patients with GPP. SP, KY and VEN contributed to the writing of the manuscript. SP constructed Table 1. All authors have read and approved the final version of the manuscript. None. None. IRB approval was not required as the study uses a publicly available data source with de-identified information. The data that support the findings of this study are available in Agency for Healthcare Research and Quality at https://www.hcup-us.ahrq.gov/db/nation/nis/nisdbdocumentation.jsp. These data were derived from the following resources available in the public domain: Healthcare Cost and Utilization Project, https://www.hcup-us.ahrq.gov/db/nation/nis/nisdbdocumentation.jsp.