Temporal Trends in Mortality Rates among Kaiser Permanente Southern California Health Plan Enrollees, 2001-2016

Area of Science:

• Public Health
• Epidemiology
• Biostatistics

Background:

• National analyses reveal a consistent decline in all-cause and major cause-specific mortality rates in the US.
• Understanding mortality trends within large, insured populations is crucial for public health surveillance.

Purpose of the Study:

• To analyze mortality trends within Kaiser Permanente Southern California (KPSC), a large insured cohort.
• To compare KPSC mortality trends with those observed in California and the overall US population.

Main Methods:

• Age-adjusted all-cause and cause-specific mortality rates were calculated for KPSC, California, and the US from 2001 to 2016.
• Data linkage with California State death files was utilized for comprehensive analysis.
• Average annual percent changes (AAPC) and 95% confidence intervals (CI) were computed to assess trend significance.
• Race/ethnicity-specific mortality trends were also examined.

Main Results:

• Significant decreases in age-adjusted all-cause mortality rates were observed in KPSC (AAPC = -1.84%), California (AAPC = -1.60%), and the US (AAPC = -1.10%).
• Mortality rates for cancer and heart disease also showed significant declines across all three populations.
• No statistically significant differences were found when comparing KPSC mortality trends with California or US trends for all-cause and top 10 cause-specific mortality rates.
• Race/ethnicity-specific, sex-specific, and combined race/ethnicity- and sex-specific mortality trends did not significantly differ between KPSC and California/US.

Conclusions:

• Mortality trends in the KPSC insured population are comparable to those observed in the broader California and US populations.
• The study supports the generalizability of national mortality trend findings to large, integrated healthcare systems.