Community-based Investigation of the Risk Factors for Cardiovascular Diseases in Ibadan and suburbs (COMBAT-CVDs): Design and Methods

Africa is gradually becoming the epicentre for the burden of cardiovascular diseases (CVDs) worldwide, and community-based data alluding to the pattern and dynamics of escalating epidemiological thresholds of CVDs among indigenous Africans are limited. This manuscript focuses on the design and methods of Community-based Investigation of the Risk Factors for Cardiovascular Diseases in Ibadan and suburbs (COMBAT-CVDs), an ongoing community-based door-to-door study assessing the profile, burden and dynamics of CVDs risk factors among residents of Ibadan and suburbs. COMBAT-CVDs is a cohort of community-dwelling indigenous Africans, males and females, ≥18years from ten communities in Ibadan, Nigeria. The recruitment of participants for the first wave (W₀) started in 2020, covering; questionnaire administration and physical examination. The World Health Organization's STEPS Instrument for Chronic Disease Risk Factor Surveillance was used for data collection. Data were collected on sociodemographic, socioeconomic and lifestyle-related characteristics, history of CVDs, stress, depression and sleep quality. Also, anthropometric and blood pressure measures were conducted by trained personnel using standard operating procedures and instruments. Data collection for the second wave is underway, and the collection of blood and other biological samples for genetic epidemiology is planned, subject to availability of funds. For the W₀ recruitment, a total of 3638 community-dwelling adults (males - 54.6% and females - 45.4%) participated with a ≥99.7% response rate. The COMBAT-CVDs will likely provide novel data, insightful characterization of CVDs risk factors and evidence for context-specific and culturally relevant interventions for the community-based prevention and management of CVDs among Africans in this setting.

The Gambian National Impregnated Bed Net Programme: evaluation of effectiveness by means of case-control studies

Two case-control studies, one on mortality and the other on malaria morbidity, were carried out in order to evaluate the impact of the Gambian National Insecticide Bed Net Programme during the second year of intervention and to explore the feasibility of such a study for the evaluation of programme effectiveness. For the mortality study, children 1-9 years old who died during the 1993 rainy season were matched by age and sex with 2 healthy controls from the same village. For the morbidity study, children 1-9 years old attending Fatoto or Jahalia Health Centres in The Gambia and who had fever and parasitaemia > or = 5000/microL were matched by age with a child attending the health centres without fever or parasitaemia. An additional healthy control was recruited from the case's village. No impact of insecticide-treated bed nets on mortality was detected and this was in keeping with the results obtained by prospective surveillance. A protective effect of insecticide-treated nets on malaria morbidity was detected when cases were compared with controls recruited at the health centres. However, this disappeared when cases were compared with controls recruited from the cases' villages. The mortality case-control study suggested that reducing the time between onset of disease and treatment may have an important impact on childhood mortality. In order to calculate programme cost-effectiveness, important for informed resource allocations to be made by health managers, it is essential to obtain evidence of effectiveness. This can be done by means of case-control studies, which are easier to carry out and require fewer resources than prospective surveillance. Nevertheless, it is necessary to be conscious of their pitfalls, particularly of the bias involved in the choice of cases and controls. The measurement of insecticide on the nets of the cases or controls is essential for such studies.

The impact of charging for insecticide on the Gambian National Impregnated Bednet Programme

During the second year of the Gambian National Impregnated Bednet Programme (NIBP) charges for insecticide ($0.50 per net) were introduced into the half of the primary health care villages in the country where insecticide have been provided free of charge the previous year. Free insecticide was provided in the remaining villages that had acted as controls during the previous year. In villages where insecticide was provided free, 77% of nets were treated with insecticide. In contrast, in villages where charges were made coverage was only 14%. During the first year of the NIBP, mortality in children was significantly lower in villages where insecticide was provided free than in the control villages. Introduction of a charge for insecticide into the first group of villages and the provision of free insecticide in the latter abolished this difference. The cash income of rural Gambians is very limited and payment of even $2-3 for insecticide treatment for all the bednets in a household represents a substantial outlay. Further education on the benefits of treatment of nets and/or the provision of cheaper insecticide will be required before the full benefits of this powerful new malaria control measure can be fully realised in the Gambia.