Mortality odds ratio, proportionate mortality ratio, and healthy worker effect

Area of Science:

• Occupational health
• Epidemiology
• Biostatistics

Background:

• Assessing occupational exposure risks often lacks complete population data.
• Standardized proportionate mortality ratio (PMRi) and mortality odds ratio (MORi) are used to estimate cause-specific standardized mortality ratio (SMRi) in such scenarios.
• The healthy worker effect can influence the accuracy of these estimations.

Purpose of the Study:

• To evaluate the performance of PMRi and MORi in approximating SMRi under conditions of unknown population risk.
• To understand the impact of the healthy worker effect on these mortality ratios.
• To provide recommendations for using these statistics in occupational risk assessment.

Main Methods:

• Comparative analysis of PMRi and MORi against SMRi.
• Examination of statistical behavior under varying disease prevalence and healthy worker effect magnitudes.
• Utilizing death certificate data as the primary data source.

Main Results:

• MORi consistently overestimates SMRi when a healthy worker effect is present and is always greater than PMRi.
• PMRi's accuracy depends on the cause of death's frequency; it overestimates for rare diseases (e.g., brain cancer, leukemia) similarly to MORi.
• For common conditions (e.g., lung cancer), PMRi may overestimate or underestimate SMRi based on the healthy worker effect's strength.
• When SMRi = 1 and a healthy worker effect exists, both PMRi and MORi exceed 1.
• As SMRi increases, PMRi tends to be the lower bound and MORi the upper bound.

Conclusions:

• Both PMRi and MORi are valuable when only death data is available for occupational risk assessment.
• MORi provides an upper bound and PMRi a lower bound for SMRi, especially for common diseases.
• Deriving both statistics is recommended for a comprehensive risk assessment using death certificates.