Extending the Peters-Belson approach for assessing disparities to right censored time-to-event outcomes

Sex disparities in the incidence of 21 cancer types: Quantification of the contribution of risk factors

BACKGROUND

Cancer incidence is higher in men than in women at most shared anatomic sites for currently unknown reasons. The authors quantified the extent to which behaviors (smoking and alcohol use), anthropometrics (body mass index and height), lifestyles (physical activity, diet, medications), and medical history collectively explain the male predominance of risk at 21 shared cancer sites.

METHODS

Prospective cohort analyses (n = 171,274 male and n = 122,826 female participants; age range, 50-71 years) in the National Institutes of Health-AARP Diet and Health Study (1995-2011). Cancer-specific Cox regression models were used to estimate male-to-female hazard ratios (HRs). The degree to which risk factors explained the observed male-female risk disparity was quantified using the Peters-Belson method.

RESULTS

There were 26,693 incident cancers (17,951 in men and 8742 in women). Incidence was significantly lower in men than in women only for thyroid and gallbladder cancers. At most other anatomic sites, the risks were higher in men than in women (adjusted HR range, 1.3-10.8), with the strongest increases for bladder cancer (HR, 3.33; 95% confidence interval [CI], 2.93-3.79), gastric cardia cancer (HR, 3.49; 95% CI, 2.26-5.37), larynx cancer (HR, 3.53; 95% CI, 2.46-5.06), and esophageal adenocarcinoma (HR, 10.80; 95% CI, 7.33-15.90). Risk factors explained a statistically significant (nonzero) proportion of the observed male excess for esophageal adenocarcinoma and cancers of liver, other biliary tract, bladder, skin, colon, rectum, and lung. However, only a modest proportion of the male excess was explained by risk factors (ranging from 50% for lung cancer to 11% for esophageal adenocarcinoma).

CONCLUSIONS

Men have a higher risk of cancer than women at most shared anatomic sites. Such male predominance is largely unexplained by risk factors, underscoring a role for sex-related biologic factors.

Statistical Approaches to Assessing Health and Healthcare Disparities

Determining whether racial and ethnic disparities exist for a health-related outcome requires first specifying how outcomes will be measured and disparities calculated. We explain and contrast two common approaches for quantifying racial/ethnic disparities in health, with an applied example from nursing research. Data from a national for-profit chain of nursing homes in the US were analyzed to estimate racial/ethnic disparities in incidence of pressure ulcer within 90 days of nursing home admission. Two approaches were used and then compared: logistic regression and Peters-Belson. Advantages and disadvantages of each approach are given. Logistic regression can be used to quantify disparities as the odds of the outcome for one group relative to another. Peters-Belson can be used to quantify an overall disparity between groups as a risk difference and also provides the proportion of that disparity that is explained by available risk factors. Extensions to continuous outcomes, to survival outcomes, and to clustered data are outlined. Both logistic regression and Peters-Belson are easily implementable and interpretable and provide information on the predictors associated with the outcome. These disparity estimation methods have different interpretations, assumptions, strengths, and weaknesses, of which the researcher should be aware when planning an analytic approach.

Are there racial-ethnic disparities in time to pressure ulcer development and pressure ulcer treatment in older adults after nursing home admission?

OBJECTIVE

The objective of this study was to assess whether there are racial and ethnic disparities in the time to development of a pressure ulcer and number of pressure ulcer treatments in individuals aged 65 and older after nursing home admission.

METHOD

Multi-level predictors of time to a pressure ulcer from three national surveys were analyzed using Cox proportional hazards regression for White Non-Hispanic residents. Using the Peters-Belson method to assess for disparities, estimates from the regression models were applied to American Indians/Alaskan Natives, Asians/Pacific Islanders, Blacks, and Hispanics separately resulting in estimates of expected outcomes as if they were White Non-Hispanic, and were then compared with their observed outcomes.

RESULTS

More Blacks developed pressure ulcers sooner than expected. No disparities in time to a pressure ulcer disadvantaging other racial/ethnic groups were found. There were no disparities in pressure ulcer treatment for any group.

DISCUSSION

Reducing disparities in pressure ulcer development offers a strategy to improve the quality of nursing home care.

Racial and Ethnic Disparities in Time to Cure of Incontinence Present at Nursing Home Admission

As many as half of older people that are admitted to nursing homes (NHs) are incontinent of urine and/or feces. Not much is known about the rate of cure of incontinence present at NH admission, but available reports suggest the rate is low. There have been racial and ethnic disparities in incontinence treatment, but the role of disparities in the cure of incontinence is understudied. Using the Peters-Belson method and multilevel predictors, our findings showed that there were disparities in the time to cure of incontinence for Hispanic NH admissions. A significantly smaller proportion of older Hispanic admissions were observed to have their incontinence cured and cured later than expected had they been White. Reducing disparities in incontinence cure will improve health outcomes of Hispanic NH admissions. Significant predictors in our model suggest strategies to reduce the disparity including attention to managing fecal incontinence and incontinence in those with cognitive impairment, improving residents' functional status, and increasing resources to NHs admitting older Hispanics with incontinence to develop innovative and cost effective ways to provide equitable quality care.