[Epidemiological characteristics of spontaneous subarachnoid hemorrhage cases in Shandong province]

Objective: To investigate the characteristics and trends of spontaneous subarachnoid hemorrhage (SAH) in Shandong province. Methods: In this study, SAH incidence data of residents from 2012 to 2021 were collected from the chronic disease monitoring information management system of Shandong province, including the basic information of outpatient, emergency or inpatient cases and out-of-hospital deaths (name, gender, ID number, address, etc.) and disease diagnosis information (disease diagnosis, date of onset, date of diagnosis, etc.). The crude incidence rate and age-standardized incidence rate were used as indicators to describe the incidence of SAH in different gender, age groups and regions (urban and rural areas). Joinpoint regression was used to analyze the variation of incidence rate and age by year. The rate difference decomposition method was used to estimate the contribution of population aging to the increase of SAH incidence. Global and local spatial autocorrelation analysis was performed using DeoDa 1.12 software. Results: From 2012 to 2021, a total of 11 629 cases of SAH were reported from 19 provincial monitoring sites in Shandong province. Among them, 54.11% (6 293 cases) were female and 91.87% (10 684 cases) were≥45 years old. The reported crude incidence rate increased from 5.26/100 000 to 9.50/100 000, with an average annual increase of 7.75% (Z_trend=7.30, P_trend<0.001), and the standardized incidence rate also showed an upward trend (Z_trend=3.92, P_trend=0.004). The crude incidence rate of women was higher than that of men in all years (all P values<0.05), and the standardized incidence rate of women was higher than that of men in all years except in 2012 and 2021 (all P values<0.05). In 2012, the crude incidence and standardized incidence of urban residents were lower than those in rural areas (P<0.05); from 2013 to 2017, the urban incidence was higher than that in rural areas; and after 2018, the rural incidence exceeded the urban incidence again (all P values<0.05). The median age of onset of SAH increased from 61.9 years in 2012 to 67.2 years in 2021. The age of onset of SAH in men was lower than that in women in all years (all P<0.05), and there was no significant difference between urban and rural residents in most years (P>0.05). The incidence of SAH increased with age (P_trend<0.001), with a low incidence reported in residents aged<45 years and a rapid increase in residents aged≥45 years. According to the seasonal decomposition, the incidence of SAH had three small peaks in January, March to May and October to November. From 2013 to 2021, the contribution of aging population to the increase of crude incidence of SAH increased from 27.86% to 43.68%. The global spatial autocorrelation analysis showed that the incidence of SAH was in an obvious spatial aggregation distribution (Moran's I>0, P<0.05). Local spatial autocorrelation analysis showed that the counties with high incidence were mainly concentrated in Dezhou City in northwest Shandong Province and Heze city in southwest Shandong province. Conclusions: The crude incidence rate of SAH in Shandong province is increasing, with spatial clustering and seasonal clustering. Residents aged 45 years and older, female residents, and rural residents are at high risk of developing SAH, so targeted prevention and control measures should be taken for high-incidence seasons, high-risk groups, and high-incidence clustered areas.