While England’s national death rate from coronary heart disease has been dropping steadily for nearly 2 decades – and by two-fifths in the last decade alone – stubborn disparities have remained along local lines, with some areas proving consistently worse off relative to others.
Findings published online Nov. 10 in JAMA suggest that although most factors associated with coronary heart disease (CHD) deaths lay in locally varying population characteristics such as smoking, ethnicity, and socioeconomic deprivation, areas that recorded a lower prevalence of hypertension saw higher CHD mortality rates, too – possibly because health services were being underused or some local primary care trusts were diagnosing and managing this CHD risk factor more effectively than others.
In short, "your post code may affect your chances of dying of coronary heart disease," the study’s lead author Dr. Louis S. Levene of the University of Leicester (England) said in an interview. The study, which examined publically available data for 2006, 2007, and 2008, covered England’s total population of about 54 million (JAMA 2010;304:2028-34).
Using a hierarchical regression model, Dr. Levene and his colleagues sought to examine the relationship between variations in coronary heart disease mortality among England’s 152 local primary care trusts and differences in any potentially explanatory factors associated with the populations they served and the delivery of health services. In 2008, the national age-standardized CHD mortality rate was 88.4/100,000 population in England (down from 97.9 in 2006 and 93.5 in 2007). Among individual local trusts, the age-standardized CHD mortality varied between 45.3 and 147.1/100,000.
The final model derived from the analysis explained about two-thirds of the variation in CHD mortality, consistent across the 3 years studied. In this model four of the five factors shown to correlate with higher local CHD mortality were population based: trusts with more white people (when examined independently of other risk factors), greater socioeconomic deprivation, more smokers, and more people with diabetes. This, Dr. Levene said, was not entirely a surprise.
The investigators also identified, however, an important service-related factor in trusts with higher CHD mortality, also consistent in the 3 years: less diagnosis of hypertension. This explained about 10% of the variation.
For example, while the Health Survey for England, an annual population study designed to measure health and health-related behaviors, saw rates of diagnosed and expected prevalence levels of diabetes that were very close in 2008, Dr. Levene and his colleagues saw a significant disparity the same year with hypertension. Only 13% of England’s population was recorded on practice registers as having hypertension, they noted, "although the Health Survey for England found a prevalence of hypertension of 30.1% among adults."
Dr. Levene said he did not know whether to ascribe the gap to underutilization of health services or a failure of the trusts to deliver preventive care. "A standard GP appointment lasts 10 minutes," he said in an interview, which may mean blood pressure checks are not done even though they are recommended by guidelines. "In my practice we have 13,000 patients – if someone comes in to see you for depression, we may try and remember to do [blood pressure]," he said. "People are getting better at doing it, since rates of diagnosis are going up."
Dr. Levene and his colleagues noted some of the limitations of their study, which included the possibility of having omitted or neglected potentially relevant factors, such as access to or continuity of health services. One missing potential population variable was sex, they wrote, "because the age-standardized CHD mortality rates are higher in men than in women." No other variables used were sex specific, so the effect of sex could not be analyzed.
Nonetheless, the investigators wrote, the findings had several policy implications. "Programs to reduce [CHD] mortality should address those characteristics of populations amenable to intervention, including smoking and deprivation. The importance of paying attention to population characteristics is emphasized by the finding that better detection of hypertension in the population was associated with reduced CHD mortality at the population level."
"My personal view," Dr. Levene told this news organization, "is that if collectively we become more interested in primary prevention in the wider population, this rate of decline should continue and the gaps should narrow."
The study was funded through the National Institute for Health Research. One of Dr. Levene’s coauthors, Dr. Kamlesh Khunti, reported being an adviser to the National Screening Committee and a clinical adviser for the Diabetes National Institute for Clinical Excellence-led Quality and Outcomes Framework Panel. No other authors reported any financial disclosures.