Case fatality rate of hand, foot and mouth disease in children aged 0–9 years in China, 2009–2021, a study based on different age–period–cohort models

Objective To explore the age, period, and birth cohort specific trends of the case fatality rate of hand, foot and mouth disease (HFMD) case fatality rate (CFR) among children aged 0–9 years in China based using different various age-period-cohort (APC) models.

Methods The incidence and death data of HFMD cases and deaths inamong children aged 0–9 years in China from 2009 to 2021 were collected. An basic APC model, a simplified parameter-based APC model, and a Bayesian APC model were used to analyze examine the trends in the CFR of HFMD nationwide. Age, period, and cohort references were set to 4 years, 2015, and 2010, respectively, and relative risks (RR) and with 95% confidence intervals (CI) were calculated. The average annual percent change (AAPC), the average unit percent change (AUPC), and the 95%CI were used to evalaute the changedetermine whether a trends change existed AAPC, AUPC, and their 95%CI were used to determine the presence of trends.

Results From 2009 to 2021, a total of 23 783 967 HFMD cases and 3 565 deaths of HFMD were reported in China, with the CFR was of 14.99 per 100 000. The analysis using the basic APC model revealed a declining trend in the case fatality rate CFR (AAPC = −31.30%, 95%CI: −37.55%-−25.06%). The difference in age-specific CFR trends were not statistically significant (χ²=9.738, P=0.284), while the birth cohort specific risk for HFMD death showed a decreasing risk trend of HFMD fatality (χ²=53.230, P<0.001). In the simplified parameter-based APC model analysis, the differences in level and age slope parameters were statistically significant (P<0.005), same for as were some period parameters (P<0.05). However, neither the birth cohort slope nor the birth cohort related factor parameters were showed significant differences (P>0.058). The Bayesian APC model analysis indicated a declining CFR with increasing age (AUPC = −74.81%, 95%CI: −79.35%-−70.28%) and period (AUPC = −53.26%, 95%CI: −67.21%-−39.32%), but no notable trends were found in different in relation to birth cohorts (AUPC = −0.02%, 95%CI: −0.16%-0.11%).

Conclusion The CFR of HFMD in China showed significant age and period specific trends, decreasing with increasing age and period, while no birth cohort specific trend effect was observed.