USA‐Caribbean Alliance for Health Disparities Research (USCAHDR)

GA-CDRC Investigators:

Ian R. Hambleton (Barbados PI), Christina Howitt, Nigel Unwin.

Other UWI Investigators:

E. Nigel Harris (Co‐PI), Madhuvanti M. Murphy, Natasha Sobers‐ Grannum, Faculty of Medical Sciences, Cave Hill Campus; Brigitte Collins. Rainford Wilks (Jamaica PI), Nadia Bennett, Trevor Ferguson, Damian Francis, Novie Younger‐Coleman, Epidemiology Research Unit, CaIHR.

External Investigators:

Funding Obtained:

National Institute on Minority Health and Health Disparities (NIMHD) (Award value: USD 5 million over 5 years)

Start Date:

June 2011

End Date:

May 2016

Rationale:

The NIMHD has funded a 5‐year program (NIH number: U24MD006959) to explore and compare for the first time health disparities among African‐descent populations in the Caribbean and the US. This partnership between the Sullivan Alliance [16] and The University of the West Indies [17] is using published work, Caribbean health databases, and open‐access data to build an evidence‐based picture of Caribbean health disparities. It is anticipated that with the creation of a comprehensive disparities situation analysis for the region, priorities for public health  both regionally and on a country‐level can then be  based  on  contextually relevant evidence.

Methods:

The project is divided into three work packages:

• The Evidence Work‐package has adopted a standardized protocol for the synthesis of non‐ randomized evidence, and is systematically assessing current evidence in six health domains: diabetes, cardiovascular disease, cancer, asthma, chronic obstructive pulmonary disease, and depression.
• The Analysis Work‐package is divided into three parts. Ecological (country‐level) analyses (part one) set the scene for in‐depth analyses of within‐country health disparities (part two), with Caribbean disparities compared to relevant US populations (part three). Major data sources for ecological analyses include the United Nations World Population Prospects, The World Health Organization Mortality Database, and The Center for Disease Control WONDER database.
• The E‐platform Work‐package A new health disparities data repository is being developed. This repository is already being used by the analysis team to produce analytical output on Caribbean and US health disparities. This repository will be a significant resource for future secondary analyses of health and health disparities in the Caribbean. To date the project has identified data resources from within the University of the West Indies (UWI) and from other data providers. Seven major UWI databases have been retrieved and prepared for analysis, totalling about 20,000 participant records. So far, seventy‐one (71) databases have been identified from external sources, totalling over 242,000 participant responses. Permissions have been sought and received to store and use 49 of these databases (213,000 participant responses), and the USACAHDR analysis team is currently preparing these databases for analysis – with 10 databases prepared so far (53,000 participant responses).

Main Results:

Evidence work‐package

Our systematic review (SR) work has initially focussed on the social distribution of 6 disease outcomes, their risk factors and major complications in the Caribbean. From two published diabetes reviews we identified 50 articles from 27 studies, yielding 118 relationships between gender and the outcomes. Women were more likely to have DM, obesity, be less physically active but less likely to smoke. In meta‐analyses of good quality population‐based studies odds ratios for women vs. men for DM, obesity and smoking were: 1.65 (95% CI 1.43, 1.91), 3.10 (2.43, 3.94), and 0.24 (0.17, 0.34). Female gender is a determinant of DM prevalence in the Caribbean. In the vast majority of world regions women are at a similar or lower risk of type 2 diabetes than men, even when obesity is higher in women. Caribbean female excess of diabetes may be due to a much greater excess of risk factors in women, especially obesity. These findings have major implications for preventive policies and research.

Analysis work‐package

Ecological analyses have explored changes in life expectancy (LE) and mortality over time, and reported LE trends since 1965 are described for three geographical sub‐regions: the Caribbean, Central America, and South America. LE disparities are explored using a suite of absolute and relative disparity metrics, with measurement consensus providing confidence to observed differences. LE has increased throughout Latin America and the Caribbean. Compared to the Caribbean, LE has increased by an additional 6.6 years in Central America and 4.1 years in South America. Since 1965, average reductions in between‐country LE disparities were 14% (absolute disparity) and 23% (relative disparity) in the Caribbean, 55% and 51% in Central America, 55% and 52% in South America.

The LE improvement among African Americans exceeded that of Afro‐Caribbeans so that the LE gap, which favoured the Caribbean population by 1.5 years in 1990, had been reversed by 2009. This relative improvement among African Americans was mainly the result of the improving mortality experience of African American men. Between 2000 and 2009, Caribbean mortality rates in 5 of the 6 disease groups increased relative to those of African Americans. By 2009, mortality from cerebrovascular diseases, cancers, and diabetes was higher in Afro‐Caribbeans relative to African Americans, with a diabetes mortality rate twice that of African Americans and 4 times that of White Americans.

Expected Impact:

These data are focussing attention of major policy makers within the Caribbean, including Chief Medical Officers and Ministers of Health, on the fact that much of the Caribbean has performed relatively poorly in health terms over the past 20 years and on the reasons underlying this poor performance. The data draw particular attention to the importance of non‐communicable diseases. These data are contributing to an evaluation of the 2007 Port of Spain Declaration on NCDs, and will therefore assist in renewed efforts to increase policy formulation and implementation on NCDs in the Caribbean.

Next Steps / Future Plans:

Proposed researches as following:

(PROPOSED RESEARCH A): Understanding the basis of Caribbean gender differences in NCD risk. Evidence gathered from our systematic reviews has demonstrated marked gender differences in patterns of Caribbean NCD risk, such as higher prevalence of obesity in women, and higher prevalence of smoking in men. This has implications for targeting health education, and for the promotion of population‐level health interventions. Anecdotal evidence on reasons for Caribbean gender differences exists and has led to hypotheses for these differences, especially for obesity, but no systematic evidence exists. In this initial qualitative investigation we will explore aspects of gender differentiation in health risk in the Caribbean.

(PROPOSED RESEARCH B): Health outcomes by socioeconomic position other than gender. Evidence gathered from our systematic reviews has highlighted the lack of information on NCDs by measures of socio‐economic position, apart from gender. Data do exist, usually stratified by education and occupation, and sometimes by income for many countries in the Caribbean, with data for some countries collected at multiple times. In this project we will focus on the secondary analysis of Caribbean country‐level risk factor health surveys. The emphasis will be on describing age‐stratified and standardised health disparities: by sex, by socio‐economic position, and by geography. Specific goals are as follows: (i) to describe regional and country‐stratified estimates of prevalence for major chronic diseases and risk factors, providing age‐standardized rates for direct comparison with other world regions (ii) to further stratify these basic morbidity metrics by measures of socio‐economic position (eg. by sex, by educational status, by occupation) (iii) to describe baseline measures of health disparities, which could be promoted as starting values for the subsequent regional monitoring of health inequities (iv) a fourth goal will be to explore alternative methods for classifying study participants by socio‐economic position, such as neighbourhood factors drawn from census linkage.

(PROPOSED RESEARCH C): Violence and Injuries as causes of morbidity and mortality, and their social determinants. Violence and aggression is an area of known public health importance, with no systematic review to assess the current evidence on the contribution of violent behaviour to Caribbean morbidity and mortality. We hypothesize that mortality due to violent activity has restricted life expectancy gains in some parts of the Caribbean, but this association has not been systematically evaluated. We propose an initial systematic review of evidence on the levels, trends, and social determinants of violent behaviour, accompanied by a systematic secondary analysis of routine data sources.

(PROPOSED RESEARCH D): Use of mortality from ‘sentinel disorders’ to assess health system performance. Evidence gathered from our analytical work has shown marked differences in life expectancy and age‐adjusted mortality between Caribbean countries. There is a need to understand the basis for these differences for policy guidance. One approach is to determine the TMRI Quinquennial Review 2015 Page 59 of 219 contribution of conditions known to be largely preventable through effective health systems – so‐called sentinel disorders. Using secondary analyses of routine data sources, we plan to compare mortality rates from sentinel disorders between Caribbean populations. Country‐level differences imply relative functioning of health care systems and of access to effective healthcare.

(PROPOSED RESEARCH E) New: Understanding the differences in trends in CVD/DM mortality between Caribbean countries and between US states. Analyses that are currently being written up have demonstrated marked differences in mortality trends across 16 Caribbean countries between the beginning of 2000 and the end of 2009, with total age adjusted mortality decreasing by around 20% in some countries, and actually increasing in others. A major driver of these different trends in total mortality is different trends in Cardiovascular Disease and Diabetes mortality. In some countries around 90% of the decline in total mortality is due to improved CVD Diabetes mortality. In those countries where total mortality has worsened this has been associated with even bigger increases in CVD‐Diabetes mortality. CVD‐Diabetes can be consider a group of ‘sentinel disorders’ in that the major risk factors are known and amendable to modification, and that there are highly effective health care interventions.

We plan to investigate the reasons for these differences in CVD‐DM by exploring risk factors (such as smoking, blood pressure, cholesterol and obesity) and coverage of effective health care (such as effective and timely treatment of hypertension, dyslipidaemia, diabetes and acute cardiovascular events). We plan to utilise epidemiological modelling to explore drivers of change (focussing, for example, on the concept of attributable risk), and we plan to utilise systems dynamics modelling to understand the potential effect of changing selected systems inputs. This proposed research draws on research described under the theme of ‘improving health and human development through targeted interventions, economic and systems/policy analysis’.