Summary
Masters, Hummer, Powers, Beck, Lin, and Finch (2014) use age-period-cohort (APC) intrinsic estimator models on National Center for Health Statistics (NCHS) Multiple Cause of Death data (1959–2009) to decompose black-white adult mortality trends into their period and cohort components. The key finding: chronic disease mortality changes over the past 50 years have been primarily cohort-based, not period-based, meaning early-life conditions and cumulative exposures are the dominant mechanism. The post-WWII cohort experienced faster mortality reductions for blacks than whites, driving cohort-based narrowing of the black-white gap. But a troubling sign is cohort-based stalling and increases in heart disease mortality for the most recent cohorts of both blacks and whites, and a widening breast cancer disparity on both period and cohort dimensions. Published in Demography 51(6): 2047–2073.
Key Claims
- Cohort effects dominate period effects for chronic disease mortality: All-cause and chronic disease (heart disease, stroke, cancer) mortality trends over 1959–2009 are primarily cohort-based, not period-based, for black and white men and women alike — consistent with Yang (2008). Estimated deaths per 100,000 show substantially larger variation across cohorts than across periods when age and the other temporal dimension are held constant.
- Pre-WWII cohorts: whites gained more than blacks. The black-white relative rate ratio in men's adult mortality rose from ~1.25 for cohorts born before 1900 to ~1.75 for cohorts born in the late 1930s/early 1940s. Institutionalized racism, segregation, and exclusion from social/public health advances prevented black cohorts from benefiting equally from improvements in the first half of the 20th century.
- Mid-1960s period shock for blacks: Rapid period-based reductions in black mortality occurred during 1965–1979, especially for black women, following the Civil Rights Act, Medicaid/Medicare enactment (1965), and Food Stamp Act (1964). This "period shock" rapidly closed the black-white period-based mortality gap for women.
- Post-WWII cohorts: blacks closed the cohort gap (Hypothesis 1 confirmed). Cohort-based reductions in black men's and women's all-cause mortality were substantially faster among post-WWII birth cohorts — driven by improved access to education, decent wages, medical care, and a weakening "color line." The black-white relative rate ratio for men fell from ~1.75 (1940s cohorts) to ~1.25 (1960s cohorts) on a cohort basis.
- Chronic disease narrowing is the main mechanism (Hypothesis 2 confirmed). Heart disease, stroke, non-lung/non-breast cancers: recent black cohorts' mortality reductions outpaced white reductions, narrowing the cohort-based gap substantially. Lung cancer also narrowed across recent male cohorts. Heart disease shows impressive period-based reductions as well.
- Troubling sign: cohort-based stalling/increases in heart disease for the most recent cohorts. Recent cohorts of BOTH black and white men and women show stalling or increasing cohort effects for heart disease mortality, likely reflecting the obesity epidemic. This warning appears in cohort data but is masked by period analyses.
- Breast cancer: the worst divergence. Both period- and cohort-based trends are widening the black-white gap. White women experienced rapid period-based reductions in breast cancer mortality since 1985 (mammography, Komen campaigns, improved treatment). Black women experienced period-based increases through the early 1990s, likely driven by the obesity epidemic and differential access to screening. Black women's cohort reductions are also slower. This is a public health emergency: a preventable cancer where racial disparities are growing on both temporal dimensions.
- Young adult mortality: period effects dominate (Hypothesis 3 confirmed). HIV/AIDS, homicide, and accidents at ages 15–34 show primarily period effects, more pronounced for blacks. Recent period reductions in HIV and homicide mortality have been especially large for blacks, driving period-based convergence.
- Early signal of Deaths of Despair: Recent period-based increases in accident mortality (ages 15–34) for white men and women — while the trend for black men and women continues downward — foreshadow the Deaths of Despair literature. These white increases likely reflect drug overdoses (pharmaceutical and illicit).
- 75,000–100,000 excess premature deaths per year for blacks vs. whites. Despite substantial progress, the raw scale of remaining disparate mortality burden is enormous.
Concepts Introduced or Extended
Entities Mentioned
Quotes
"Changes in U.S. black and white all-cause mortality between 1959 and 2009 exhibited more pronounced cohort trends than period trends."
"Cohort-based reductions in black men's and women's all-cause mortality were faster among birth cohorts born after WWII than among cohorts born earlier in the twentieth century."
"Both period- and cohort-based changes in black women's breast cancer mortality trended worse than the respective patterns in white women's breast cancer mortality."
"Black-white differences in U.S. adult mortality have narrowed over the past five decades... [but] cohort-based stalling and increasing rates of heart disease mortality among recent cohorts of black and white men and women are a particular concern."
My Take
This is a technically sophisticated and theoretically grounded paper that substantially advances the Mortality by Race and Ethnicity literature. The main contribution is showing that the dominant mechanism for the post-WWII narrowing of the black-white mortality gap is cohort-based — meaning it reflects improvements in early-life conditions, education, and access to healthcare for post-WWII black cohorts, not contemporaneous period interventions. This has a specific policy implication: period interventions (like expanded healthcare access) can produce rapid improvements (as the 1965 shock shows), but the underlying trajectory is set by life-course processes that take decades to play out. The breast cancer finding is the most alarming new result — it is one of the few documented cases where the racial gap in mortality is widening on both temporal dimensions simultaneously. The early foreshadowing of Deaths of Despair for white accident mortality (while blacks' accident mortality continues declining) is also notable given the paper was published before Case and Deaton (2015).