FACULTY OF PUBLIC HEALTH

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Author: search.filters.author.Akpa, O. M.Subject: search.filters.subject.epidemiology

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    Carotid IMT is more associated with stroke than risk calculators
    (John Wiley & Sons Ltd., 2015) Owolabi, M. O.; Akpa, O. M.; Agunloye, A. M.
    Background – It is unclear whether a natural marker of atherosclerosis (carotid intima-media thickness: CIMT) or calculated risk score is more associated with stroke. We therefore comparatively examined the relationship between CIMT as well as two cardiovascular risk calculators (Omnibus Risk Score -ORS and Framingham Risk Score- FRS) and the occurrence of stroke among hypertensive African patients. Methods – CIMT was measured in 555 consecutive consenting hypertensive adults (377 stroke patients and 178 strokefree subjects). The 10-year cardiovascular risk was calculated for each participant with the FRS and ORS. The strengths of association between FRS, ORS, CIMT, and stroke occurrence were examined using logistic regression. The discriminative capacity of FRS, ORS, and CIMT for stroke occurrence was assessed with c-statistics. Results – Higher average CIMT (OR 11.71; 95% CI 1.65–83.07; P = 0.01) was strongly associated with stroke after adjusting for age, sex, blood pressure, serum cholesterol, and blood sugar. Neither the FRS (OR: 1.03; CI: 0.89–1.19, P = 0.68) nor the ORS (OR: 1.08; CI: 0.90–1.30; P = 0.41) was significantly associated with stroke. CIMT had a higher c-statistic for differentiating stroke patients from hypertensive controls (right: c = 0.63, P < 0.001; left: c = 0.67, P < 0.001; average: c = 0.66, P < 0.001) than some conventional risk factors. Neither FRS (P = 0.39) nor ORS (P = 0.55) was able to independently differentiate between stroke and hypertensive patients. Conclusion – CIMT, but neither FRS nor ORS, is independently associated with stroke among Nigerian African hypertensive patients. CIMT may be a better tool for estimating the overall risk of stroke than FRS or ORS in this population.
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    Mathematical modeling of the epidemiology and the transmission dynamics of HIV/AIDS infections in Nigeria
    (College of Medicine, University of Ibadan, 2010) Akpa, O. M.; Oyeloja, B. A.
    Many of the already proposed models for the transmission of HIV/AIDS do not fit the situations in Nigeria. This is in part due to the fact that many of the models pay more attention to either homogeneity of sexual contact or population of homosexuals. Although some notable models have also been studied by different authors in times and places for heterosexual transmission of HIV/AIDS epidemics, none of these models addressed the peculiar transmission dynamics in Nigeria. In this study, we grouped the population into susceptible, infected and AIDS men and women with sexual contact as the major route for HIV transmission. Assuming a strong sexual network between the groups and with the AIDS group unable to contribute to infection, we formulated mathematical models for the heterosexual transmission dynamics of HIV/AIDS in Nigeria. Our models incorporated parameters and variables that describe the nature and the strength of the transmission across the groups. We also presented model predictions on pattern of mixing between and Within the groups and how these in turn determine the global dynamics of the epidemics in Nigeria. Our simulation results show that, an increase in the transmission probability as well as in the number of sexual partnership poses more treat to the population than other parameters. The model predictions show that the epidemics tend to level up after year 2010. The number of sexual partners change per year and the probability of an effective contact are among the most critical variables in the HIV/AIDS epidemics in a community of heterosexual Nigerians. Our results agree with recent findings of similar models for some Sub-Saharan African countries. Also, results from the predictions based on the most recent National HIV Seroprevalence Surveillance Survey conducted in Nigeria agree with our findings.
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    Modeling the transmission dynamics of HIV/AIDS epidemics: an introduction and a review
    (Open Learning, 2010) Akpa, O. M.; Oyejola, B. A.
    Introduction: One of the greatest causes of morbidity and mortality in the Sub-Saharan Africa, particularly among young adults, is HIV/AIDS. Many mathematical models have been suggested for describing the epidemiology as well as the epidemiological consequences of the epidemic. A review of some these models would aid researchers in applying them to better understand and control the incidence and distribution of the disease in their countries. Methodology: This study reviews some of the models proposed by various authors for describing the epidemiology as well as the epidemiological consequences of the HIV/AIDS epidemic and how some of them could be modified to suit the situations in other countries. We also discuss the limitations and the place of such models in the fight against the HIV epidemic. Results: A clear explanation of the premises and assumptions on which the models were based was reached by reviewing the models across different scenarios. Conclusion: Mathematical models have been very useful in HIV research, particularly for empirical studies on people living with HIV/AIDS (PLWHA). These models make predictions that generate questions of social and ethical interest.