Study on Modulation of 6-Years Survival of Disabled Due to Acute Myocardial Infarction and Stroke by the Invariant Life Style Factors and Anamnesis by Cox Modelling
About the author:
Klimenyk V. P.
Type of article:
Survival is the most informative index of clinical and social efficacy of treatment and medical care organization. That is why we used survival to study medical and social care to incapable persons due to acute myo- cardial infarction (AMI) and stroke. This problem rivets particular attention of PH policy makers, PH economists, PH managers, demographists because of substantial economic societal losses, decrease in both life quality and longevity. The related studies are in abundance in developed world still few on the ground in developing. The most relevant to purpose proved to be cohort study design. It incapacitates evaluations in person-time units of risk, adopts right censored data, and empowers assessment of survival covariates. The purpose of paper is to unveil the survival modification by the invariant life style factors and anamnesis in disabled patients with acute myocardial infarction and stroke. Data organized in joint cohort of Zhytomirska oblast over 1207-2012. Cohort comprised 533 disabled persons, 303 invalidity cases due to acute myocardial infarction and 230 due to stroke traced 6 years pro- spectively. We exploited Cox risk proportional model, classical set up with right censoring, flow sampling, discreet times. Therefore, likelihood function was of Breslow modification. Maximization was proceeded by classical New- ton-Raphson method. Inferences based upon partial effects (β) and related relative risk estimations (RR). Results. We observed higher lethality among acute myocardial infarction patients, the cumulative difference substantial from the first year and on. Observed 6-years survival was 79,5% in patients with AMI and 93,2% in patients with stroke. Cox model proved to be pick of the bunch to study partial effects on survival under classical flow sampling set up with lagged covariates and discreet time measurements. Given set of life style factors and anamnesis significantly modified survival in disabled patients with both acute myocardial infarction and stroke (р <0,0001). If patient was rural resident the risk decreased significantly (р=0,038) by 25,2% in case of AMI and by 76% in case of stroke. Age-ing with brackets «30 and younger», «30-40», «40-50», «50-60», «60-70», «older then 70» significantly (р=0,040) increased lethality. Each consequent age group significantly (p<0,040) increased lethality by 26% in AMI patients and by 149% in patients with stroke. Favorable social status of disabled person significantly (р=0,033) decreased lethality in case of AMI by 25,4%. Yet more pronounced decrease (74%) observed in disabled due to stroke. Time from incidence to hospitalization also significantly (р=0,036) moderated survival. Each consequent category in hours («less than 6», «6-12», «12-24», «more then 24») enhanced lethality by 44% in case of AMI and by 51% in case of stroke. Comorbidity measured by Charlson comorbidity index significantly increased lethality by 69% in patients with stroke only. One plausible explanation is observed different survival due to concomitant pathology of patients with AMI and stroke. The most influential appeared to be obesity and severity of patient’s condition. Obesity sig- nificantly increased lethality by 139% in AIM patients and by 46% in patients with stroke. Each successive grade of severity of patient’s condition in time of hospitalization «moderate», «severe», «very severe») leveled up lethality by 98% in patients with AMI and by 177% in patients with stroke (р<0,05).
disability, acute myocardial infarction, stroke, survival
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Publication of the article:
«Bulletin of problems biology and medicine» Issue 3 part 1 (110), 2014 year, 157-163 pages, index UDK 614. 2:517. 004. 13:519. 46(014)