Indirect Effects of Municipal Public Health Nurse Workforce on Cancer Standardized Mortality Ratios Mediated by Cancer Screening Rates

Abstract

Objective: This study examined the indirect effects of the number of Japanese municipal public health nurses (PHNs) on cancer standardized mortality ratios (SMRs), using cancer screening and diagnostic follow-up rates as mediators. Design: Ecological study using municipalities as the unit of analysis. Measurements: Aggregate, municipal-level government data were analyzed using a linear model with empirical Bayes estimates of SMRs (EBSMRs) for gastric, colorectal, and lung cancers as the dependent variables, and the number of PHNs, cancer screening rate, diagnostic follow-up rate, and adjustment variables as independent variables. Structural equation modeling (SEM) was used to examine the indirect effects of PHNs. Results: Cancer screening rates were significantly negatively associated with EBSMR, except for gastric cancer in women. No significant association was observed between the EBSMR and diagnostic follow-up rates. SEM revealed a significant indirect effect of the number of PHNs, most of which was due to the cancer screening rate. Conclusions: From a population-based public health perspective, increasing the number of PHNs and focusing on improving cancer screening rates may effectively reduce cancer SMRs.