The Correlation Between Orofacial Cleft Birth Prevalence and Residential Altitude: A Global, Ecological Study

Abstract

ObjectThis study aims to analyze the correlation between orofacial cleft (OFC) birth prevalence and residential altitude from a global perspective, providing more evidence for the development of early screening and prevention policies for OFC, particularly in high-altitude regions.DesignThe birth prevalence of OFC, summary exposure value of associated risk factors, and Socio-demographic Index data were extracted from the Global Burden of Disease Study 2021. Geographic altitude (GA) and global altitude-population data were extracted from published data. A novel Population Altitude Index (PAI) was developed to describe the altitude at which a country's population is primarily concentrated. Spearman correlation coefficient (R_s), multinominal logistic regression, partial correlation analysis, Mann-Whitney U test, and paired t test were employed to analyze the relationships between OFC birth prevalence, GA, PAI, and other related factors. Sensitivity analysis was performed using the generalized linear model. The population attributable fraction was used to assess the contribution of high residential altitude to the birth prevalence of OFC.ResultsMann-Whitney U test and paired t test indicated a statistical difference between GA and PAI (P < .05). Orofacial cleft birth prevalence showed a moderate positive correlation with PAI (R_s = 0.31, P < .05), stronger than with GA (R_s = 0.21, P < .05). Partial correlation analysis, multinominal logistic regression, and generalized linear model confirmed PAI's independent association with OFC birth prevalence after adjusting for other risk factors. A PAI threshold of 375 m yielded the largest intergroup difference (Cohen d = -0.65). The estimated population attributable fraction for OFC birth prevalence in regions with a PAI >375 m was 9.9% (lower: 4.7%, upper: 14.1%).ConclusionResidential altitude, particularly when assessed by PAI, is positively associated with national and regional level OFC birth prevalence. The PAI may serve as a valuable index for future altitude-related epidemiological studies.

Keywords: altitude; birth prevalence; global epidemiology; orofacial cleft; risk factor.