The paradox of invasive therapy following non-ST-acute coronary syndrome in older higher risk patients: A population level study in South Wales 2000-2014 IJPDS (2017) Issue 1, Vol 1:165, Proceedings of the IPDLN Conference (August 2016)

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Majd Protty
Arron Lacey
Dave Smith
Phillip Freeman
Published online: Apr 18, 2017


ABSTRACT


Objectives
Following non-ST-elevation acute coronary syndrome (NSTEACS), patients are treated with medication and considered for invasive therapy and revascularization. Mortality for this whole population is high in the first year with multiple studies suggesting anything from 4% to 10%. However, the risk of death after the first year has a wide distribution amongst the whole population with a much higher risk in older patients. We will highlight that decisions to revascularise are predominantly focused on a younger lower risk population with smaller improvements in outcome. Older, higher risk patients frequently do not receive invasive therapy despite the potential to benefit the most. However, the evidence base for using invasive therapy in this group is poor overall. With the use of data linkage from a novel national NSTEACS registry dataset we aim to clarify the influence of invasive therapy on this group in terms of adjusted mortality, reinfarction, re-admission with ischaemia, stroke and major bleeding.


Approach
All patients over a 14-year period in south Wales with a first diagnosis of NSTEACS and treated either medically or invasively. Cohorts identified by a combination of ICD-10 codes, operation codes, and linkage to coronary angiography data. Extraction of cohorts validated externally using novel national NSTEACS registry data. Multivariate analysis of baseline-characteristics for understanding how these factors influence treatment decisions. Propensity matching between medical cohorts and invasive cohorts to show the corrected effect of invasive vs. medical therapy.


Results
Total population 83,712 from 2000 until 2015. With 23,670 patients invasive therapy, 57,042 medical therapy. Invasive therapy was common in the 65-69 age groups and below but the proportion was never more than 50%. Above 65-69 exponential decline in invasive therapy, 75-79 (24.4%) 80-84 (14.7%) and 85-89 (6.5%). Unadjusted mortality revealed highly significant improvements in survival for the invasively treated patients in all age groups but with large increases as age increased. Adjusted and matched results to follow.


Conclusion
Initial results suggest increasing age and cardiovascular risk is associated with much higher mortality at one year and beyond. Older higher risk patients have very low rates of invasive revascularization but appear to have more to gain from this approach (than younger, lower risk patients), in terms of mortality and morbidity. In the older higher risk population these results suggest that increased frequency of invasive therapy will lead to reduced short and long term mortality, reduced hospital readmission with less frequent development of heart failure and reinfarction.


Objectives

Evidence of regional variation in the utilization of medical tests and procedures has raised concern surrounding the potential overuse of unnecessary care. Such overuse is detrimental as it may lead to overdiagnosis, and the resulting overtreatment of indolent disease, inefficient use of resources, and rising healthcare costs. The purpose of this study was to explore small area variation in rates of commonly used laboratory, imaging, and cardiac tests and specialist consultations, and to identify factors associated with rate variations.

Approach

This is a population-based cross-sectional study in Ontario, Canada using linked, administrative databases from the Institute for Clinical Evaluative Sciences (ICES). The study population was all adults aged 40 to 75 as of January 1, 2008. We measured the age- and sex-standardized rates of 36 laboratory, imaging and cardiac tests and specialist consultations across 97 health regions in 2008 using physician and laboratory billing data. The list of tests and consultations was chosen through discussion with primary care physicians to identify procedures that are commonly used and potentially overused in primary care settings. We compared the small area rates to the Ontario rate. We calculated small area variation statistics, including the extremal quotient (EQ), coefficient of variation (CV) and systematic component of variance (SCV), for each test and consult. We used multivariable regression models to identify factors associated with health area utilization rates.

Results

At minimum, a 10-fold difference was observed in the rates of each test and consult across the 97 health regions in Ontario, with the extremal quotients ranging from 13.6 to 54.9. When ranked in highest to lowest variation using the SCV, the tests and procedures with the greatest small area variation were limb computed tomography (EQ=49.6, CV=23.3, SCV=38.9), ferritin blood tests (EQ=42.7, CV=33.4, SCV=36.8) and vitamin B12 blood tests (EQ=40.9, CV=35.9, SCV=36.0). The test with the smallest variation was knee imaging (EQ=13.6, CV=2.1, SCV=1.7).

Conclusion

We observed substantial variation across Ontario in the utilization of 36 medical tests and consultations. These findings may indicate problems with access to care in areas with low utilization, or overuse of potentially inappropriate or unnecessary medical care in areas with high utilization. Ongoing analyses are exploring determinants of area-level utilization to better understand the observed rate variations.

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