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Open Access Publications from the University of California

Scholarly Works (54 results)

  • Article
  • Peer Reviewed
UCLA Previously Published Works (2019)

Importance

Cigarette smoking during pregnancy increases the risk of preterm birth, low birth weight, and infant mortality.

Objective

To assess the probability of preterm birth among expectant mothers who smoked cigarettes before pregnancy and quit smoking at the start or during pregnancy.

Design, setting, and participants

This cross-sectional study analyzed information provided on live birth certificates from 2011 through 2017 that were obtained from US states that implemented the 2003 revision of the US live birth certificate. In total, 25 233 503 expectant mothers who delivered live neonates and had known prepregnancy and trimester-specific cigarette smoking frequency were included in the analyses.

Exposures

Cigarette smoking frequency (1-9, 10-19, and ≥20 cigarettes per day) 3 months prior to pregnancy and for each trimester during pregnancy.

Main outcomes and measures

Cigarette smoking cessation throughout pregnancy, after the first trimester, after the second trimester, and during the third trimester irrespective of first and second trimester smoking. Probability of preterm birth (<37 weeks' gestation).

Results

Of 25 233 503 expectant mothers who delivered live neonates between 2011 and 2017, the modal age at delivery was 25 to 29 years; 52.9% were non-Hispanic white, 23.6% were Hispanic, and 14.2% were non-Hispanic black women; 22 600 196 mothers did not smoke during the 3 months prior to pregnancy, and 2 633 307 smoked during the 3 months prior to pregnancy. The proportion of prepregnancy smokers who quit throughout pregnancy was 24.3% in 2011 and 24.6% in 2017. The proportion of prepregnancy smokers who quit during the third trimester was 39.5% in 2011 and 39.7% in 2017. High-frequency cigarette smoking often occurred among expectant mothers who smoked during pregnancy (eg, 46.9% of third-trimester smokers smoked ≥10 cigarettes per day in 2017). The probability of preterm birth decreased more the earlier smoking cessation occurred in pregnancy. For example, the probability of preterm birth was 9.8% (95% CI, 9.7%-10.0%) among 25- to 29-year-old, non-Hispanic white, primigravida and primiparous expectant mothers (ie, pregnant for the first time and not yet delivered) who smoked 1 to 9 cigarettes per day prior to pregnancy and maintained this frequency throughout their pregnancy. The probability of preterm birth was 9.0% (95% CI, 8.8%-9.1%) if smoking cessation occurred at the start of the second trimester (an 8.9% relative decrease), and 7.8% (95% CI, 7.7%-8.0%) if cessation occurred at the start of pregnancy (a 20.3% relative decrease).

Conclusions and relevance

Quitting smoking-and quitting early in pregnancy-was associated with reduced risk of preterm birth even for high-frequency cigarette smokers.
    Cover page: Association of Maternal Cigarette Smoking and Smoking Cessation With Preterm Birth
    • Article
    • Peer Reviewed
    UCLA Previously Published Works (2017)
    In this paper we assess properties of commonly used estimates of total effects of obesity on mortality and identify consequences of these properties for inferences. We argue that standard estimates have important shortcomings that at best limit the reach of inferences and at worst lead to misleading conclusions. Although some of these limitations are routinely acknowledged, rarely is their use accompanied by careful scrutiny of their weaknesses, let alone by a quantitative assessment of their sensitivity to violations of some stringent assumptions on which they are based. In this paper we develop an integrated framework based on a multistate hazard model to describe properties of the simpler standard estimates, identify conditions under which their performance is best, and define the nature of biases and interpretational ambiguities that emerge when empirical conditions depart more than modestly from optimal ones. In particular, we show formally that estimates from limited panel data and two-state hazard models with obesity as a covariate, the workhorse in this area, produce estimates that are difficult to interpret and compare across studies and, in some cases, biased. Finally, we propose a simple procedure that can be employed when the use of conventional two-state models is risky and illustrate its application to an a empirical case.
      Cover page: The Impact of Obesity on Adult Mortality: Assessment of Estimates with Applications
      • Article
      • Peer Reviewed
      UCLA Previously Published Works (2018)
      The naked mole rat defies the Gompertz law and shows no sign of increased mortality risk as it gets older.
        Cover page: Age is just a number
        • Article
        • Peer Reviewed
        UCLA Previously Published Works (2019)

        Importance

        Nearly 4 in 10 expectant mothers in the United States received Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) benefits during pregnancy between 2011 and 2017. Despite public support for the program, empirical evidence of the success of the program varies substantially.

        Objective

        To assess the association of WIC program participation during pregnancy by low-income expectant mothers covered by Medicaid with infant mortality by gestational age at birth and by maternal race/ethnicity in comparison with their counterparts who did not receive WIC benefits.

        Design, setting, and participants

        This cohort study obtained data from January 1, 2011, to December 31, 2017, from US live birth certificates. Data were from 11 148 261 expectant mothers who delivered live births in states that have implemented the 2003 revision of the US live birth certificate and whose insurance coverage and receipt of WIC benefits were recorded on the birth certificates. Data analysis was performed from June 2019 to October 2019.

        Exposures

        Receipt of WIC benefits during pregnancy.

        Main outcomes and measures

        The first outcome was gestational age at birth: extremely preterm (<28 weeks), very preterm (28-32 weeks), moderate-to-late preterm (32-37 weeks), and normal term (≥37 weeks) births. The second outcome was death within the first year of life.

        Results

        Among the 11 148 261 expectant mothers who delivered live births between 2011 and 2017 and were covered by Medicaid during pregnancy, the modal age at delivery was 20 to 24 years, the predominant race/ethnicity was non-Hispanic white (4 257 790 [38.2%]), and 8 145 770 (73.1%) received WIC benefits during pregnancy. The proportion of expectant mothers covered by Medicaid who also received WIC benefits decreased from 2011 to 2017 (79.3% to 67.9%; P < .001). The odds of preterm birth compared with normal term birth were lower among expectant mothers covered by Medicaid who received WIC benefits during pregnancy compared with their counterparts who did not receive WIC benefits during pregnancy (adjusted proportional odds ratio, 0.87; 95% CI, 0.86-0.87). The odds of mortality within 1 year of birth were lower for infants whose mothers were covered by Medicaid and received WIC benefits during pregnancy compared with those who did not receive WIC benefits during pregnancy (adjusted odds ratio, 0.84; 95% CI, 0.83-0.86).

        Conclusions and relevance

        This study found that receipt of WIC benefits among expectant mothers with Medicaid coverage was associated with lower risk of preterm birth and infant mortality.
          Cover page: Association of Special Supplemental Nutrition Program for Women, Infants, and Children With Preterm Birth and Infant Mortality
          • Article
          • Peer Reviewed
          UCLA Previously Published Works (2019)
          The number of older adults is increasing in high-income countries as survival chances continue to improve. We investigate changes in survival at older ages in high-income countries and show that although survival chances have improved, these improvements are concentrated at the top of the survival distribution where there is a small share of the population. Among females who survive to age 85 in the most recently birth cohort (1925), for example, about half die within 8 years while those in the top 25% of the survival distribution live at least 50% longer (12 years or more). Importantly, these results indicate that having some individuals reach exceptionally old age does not imply that the majority of the population is living longer. In addition, estimates of lifespan inequality at older ages suggests that years of life lost because of death have increased in recent times and among recently born cohorts leading to an increase uncertainty in the age at death at older ages. Thus, slow survival improvements at ages 65+ suggest that most of the population is unlikely to reach long life expectancies in the near future, which may lead to lower than expected fraction of adults reaching older ages.
            Cover page: Period and cohort-specific trends in life expectancy at different ages: Analysis of survival in high-income countries
            • Article
            • Peer Reviewed
            UCLA Previously Published Works (2017)
            We develop a discrete variant of a general model for adult mortality influenced by the delayed impact of early conditions on adult health and mortality. The discrete variant of the model builds on an intuitively appealing interpretation of conditions that induce delayed effects and is an extension of the discrete form of the standard frailty model with distinct implications. We show that introducing delayed effects is equivalent to perturbing adult mortality patterns with a particular class of time-/age-varying frailty. We emphasize two main results. First, populations with delayed effects could experience unchanging or increasing adult mortality even when background mortality has been declining for long periods of time. Although this phenomenon also occurs in a regime with standard frailty, the distortions can be more severe under a regime with Barker frailty. As a consequence, conventional interpretations of the observed rates of adult mortality decline in societies that experience Barker frailty may be inappropriate. Second, the observed rate of senescence (slope of adult mortality rates) in populations with delayed effects could increase, decrease, or remain steady over time and across adult ages even though the rate of senescence of the background age pattern of mortality is time- and age-invariant. This second result implies that standard interpretations of empirical estimates of the slope of adult mortality rates in populations with delayed effects may be misleading because they can reflect mechanisms other than those inducing senescence as conventionally understood in the literature.
              Cover page: Discrete Barker Frailty and Warped Mortality Dynamics at Older Ages
              • Thesis
              • Peer Reviewed
              UCLA Electronic Theses and Dissertations (2024)

              Oral health is an integral component of general health. Still, too many older adults in the U.S. have no access to dental care while also suffering from disproportionate rates of oral diseases. Little has been done to address social determinants of oral health at a national level. The goal of this dissertation was to investigate the link between socioeconomic status (SES) and three indicators of oral health among U.S. older adults: (1) utilization of dental services, (2) untreated dental caries, and (3) permanent tooth loss. These outcomes mark the progression of poor oral health that begins with access to routine dental care, then advances to dental caries, and reaches the terminal outcome of permanent tooth loss. Our theoretical framework drew upon concepts from Elder’s (1974) Life Course Framework, Link and Phelan’s (1995) Theory of Fundamental Causes. and Cockerham’s (2005) Health Lifestyle Theory.

              Cross-sectional data from the (2013-2018) National Health and Nutrition Examination Survey (NHANES) were used to assess variations in oral health-related outcomes among adults aged 50 years and older. Key findings revealed that participants with lower levels of education and income were less likely to have regular dental check-ups, had a higher likelihood of untreated dental caries, and faced an elevated risk of permanent tooth loss compared to those with higher SES. These disparities linked to SES were particularly pronounced in adults over 80 years of age with limited educational attainment. Furthermore, escalating levels of food insecurity and having infrequent dental care were both associated with fewer permanent teeth, a higher risk of untreated dental caries, and a greater probability of complete tooth loss.

              The consequences of oral diseases are life-altering. Older U.S. adults are especially vulnerable to these challenges, influenced by a combination of social, behavioral, and clinical factors over their lifespan. Unfortunately, research in this area is scarce, while public programs such as Medicare do not even offer basic dental coverage. Thus, understanding critical social drivers of oral health is imperative for enhancing dental outcomes for current and future generations.

                Cover page: A Healthy Smile Can Last a Lifetime: Exploring the Social Determinants of Oral Health Among Older Adults in the U.S.
                • Article
                • Peer Reviewed
                UCLA Previously Published Works (2015)

                Objective

                To prospectively assess the relationship between overweight/obesity and incidence of type 2 diabetes mellitus (T2DM) among Mexicans aged 50+, assessing effects of age, genetic predisposition, education, physical activity, and place of residence.

                Materials and methods

                The Mexican Health and Aging Study (MHAS) was used to prospectively follow respondents free of diabetes in 2001 who became diabetic by 2012. Multivariate random effects logistic regression was used to assess covariates effects on the incidence of T2DM.

                Results

                Obese or overweight individuals at baseline (2001) were about 3 and 2 times, respectively, significantly more likely to become diabetic by 2012. Genetic predisposition increases the risk of diabetes by about three times compared to those with no family history of diabetes.

                Conclusion

                Overweight/obesity and genetic predisposition are the primary drivers of diabetes incidence among Mexican older adults. Reducing body weight and having access to health care may amel iorate the disease burden of T2DM.
                  Cover page: Prospective study of the link between overweight/obesity and diabetes incidence among Mexican older adults: 2001-2012
                  • Thesis
                  • Peer Reviewed
                  UCLA Electronic Theses and Dissertations (2024)

                  Emergency medical services (EMS) are an important entry point into the United States (U.S.) healthcare system for Hispanic older adults who often have challenges accessing preventive and diagnostic care (Melgoza et al., 2023). Between 2012 and 2050, the population of Hispanic older adults is projected to quintuple from 3.1 million to 15.4 million, although few studies assess the multi-level factors that impact provision of EMS to this population (Hummer & Hayward, 2015; Melgoza et al., 2023). The goal of this dissertation is to investigate the multi-level factors that impact provision of EMS for Hispanic older adults. The first study is a scoping literature review that provides an overview of the current state of the literature in assessing the multi-level factors that impact EMS provision for Hispanic older adults across each link in the out-of-hospital chain of survival. The second and third studies examine the multi-level factors that impact provision of EMS for two different types of emergencies: high acuity cardiac emergencies and low-acuity psychiatric emergencies. McLeroy’s (1988) Socio-Ecological Model and Link and Phelan’s (1995) Fundamental Cause Theory provide the theoretical foundation for all three studies. The Chain of Survival Framework also contributes to the theoretical foundation for the first and second studies that focus on EMS provision for cardiac emergencies. The first study used a scoping literature review methodology to identify studies across multiple databases that meet the inclusion criteria. The second and third studies use cross-sectional data from the San Francisco Department of Emergency Management (SF DEM) and the 2022 5-Year American Community (ACS). In addition to data from SF DEM and ACS, the third study also uses COVID-19 data from the San Francisco Public Health Department, eviction notices data from the San Francisco Open Data Portal, and homeless count data from the City and County of San Francisco’s Public Records Office. Key findings across all three studies suggest the importance of considering factors across multiple levels, and the interplay of these, on provision of EMS for Hispanic older adults. EMS provision for cardiac emergencies was higher among Hispanics, males, older age groups, and in geographic areas with a higher proportion of Hispanic residents, compared to Whites, females, younger persons, and geographic areas with a lower prorportion of Hispanic residents. On the contrary, EMS provision for psychiatric emergencies was higher among Whites, persons with suspected alcohol or drug use, younger age groups, and in neighborhoods with the highest number of eviction notices, but lower in neighborhoods with the highest concentration of persons who are homeless, compared to Hispanics, persons without suspected alcohol or drug use, older age groups, neighborhoods with fewer numbers of eviction notices, and neighborhoods with fewer persons who are homeless. Overall, this dissertation provides insights into provision of EMS for Hispanic older adults. The findings can inform the development, implementation, and evaluation of interventions and programs, as well as influence policies that address existing health disparities and work to achieve health equity in the prehospital setting.

                    Cover page: A Vision for Equity in Emergency Care: An Examination of the Multi-Level Factors that Impact the Provision of Emergency Medical Services to Hispanic Older Adults
                    • Article
                    • Peer Reviewed
                    UCLA Previously Published Works (2017)
                    Social inequalities in health and disability are often attributed to differences in childhood adversity, access to care, health behavior, residential environments, stress, and the psychosocial aspects of work environments. Yet, disadvantaged people are also more likely to hold jobs requiring heavy physical labor, repetitive movement, ergonomic strain, and safety hazards. We investigate the role of physical work conditions in contributing to social inequality in mobility among older adults in Mexico, using data from the Mexican Health and Aging Survey (MHAS) and an innovative statistical modeling approach. We use data on categories of primary adult occupation to serve as proxies for jobs with more or less demanding physical work requirements. Our results show that more physically demanding jobs are associated with mobility limitations at older ages, even when we control for age and sex. Inclusion of job categories attenuates the effects of education and wealth on mobility limitations, suggesting that physical work conditions account for at least part of the socioeconomic differentials in mobility limitations in Mexico.
                      Cover page: Links between Primary Occupation and Functional Limitations among Older Adults in Mexico.
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