Academic journal article Bulletin of the World Health Organization

The Absence of Adult Mortality Data for Sub-Saharan Africa: A Practical Solution

Academic journal article Bulletin of the World Health Organization

The Absence of Adult Mortality Data for Sub-Saharan Africa: A Practical Solution

Article excerpt

Introduction

The dearth of accurate and reliable adult mortality data from developing countries, both all-cause as well as cause-specific mortality rates, has been noted on a number of occasions, and the need for such data underlined[1,2]. There are clear policy applications for demographic and vital statistics in the structuring of public health interventions and health systems, which makes the absence of such data all the more frustrating[3]. The costs of this ignorance range from economic loss at the level of individual productivity[4], to overburdened health-care facilities[5], and higher levels of child mortality among the offspring of sick or deceased adults[6].

The incompleteness and unreliability, or in many cases the total absence, of national vital registration in some developing countries has made it necessary to seek other sources of information on adult mortality. In Africa, for example, only three countries reported annual cause-specific mortality data to WHO at least once between 1985 and 1989; this represents a population coverage level of 0.25 %, compared with 94% in Europe and 80% in the Americas[7].

Although estimated statistics are available for causes of death in Africa and the rest of the developing world[8], examination of the bases of these data shows that they are model-based extrapolations founded on a number of questionable sources. While it is necessary to make use of models in the absence of direct data, such an approach has the disadvantage of generating false confidence in the numbers produced. If realistic confidence intervals could be attached to vital statistics from sub-Saharan Africa, they would be so wide that the statistic in question would be considered essentially unknown.

The above critique should not be misconstrued as an attack on those who have tried to make the best of this limited information base, all the while emphasizing the inadequacy of present sources and arguing that more attention be paid to this issue (2). Rather, our purpose is to review the major weaknesses of existing estimates, including the following: statistics that are based on outdated studies; nonrepresentative samples, studies of insufficient size to provide stable estimates; or no data whatsoever.

Murray has critiqued the practice of presenting vital statistics without adequate explanation of their source[9]. Annual life expectancy and infant mortality data are presented in many reference works; however, particularly for sub-Saharan Africa, the information is obtained by applying demographic models to an extremely small database. Also, the assumptions and empirical foundations of such models are rarely stated, and the choice of parameters can lead to very large differences in the final estimates. Unfortunately, even in the best of cases, these parameters are drawn from data that are outdated or unrepresentative; and all too often they have no empirical basis at all. The World Bank's estimates of adult mortality in Nigeria, for example, are calculated from a hypothetical age pattern of mortality that was derived "qualitatively" from a mix of data from neighbouring countries and a few small studies of childhood mortality in the 1970s[10].

Clearly, it is the small number of informative studies that forces researchers to consider sources that are out of date. For example, in a comprehensive discussion of chronic disease epidemiology in sub-Saharan Africa, Hutt cited 122 references, 61 of which were more than 20 years old[11]. The published literature is therefore increasingly irrelevant to current conditions and trends and should be used with caution.

The limitation inherent in unrepresentative study samples can be levelled against the common source data on cause-specific adult mortality in sub-Saharan Africa: hospital-based studies and clinical series. Timaeus has concluded that in much of sub-Saharan Africa, such statistics are of limited utility [12]. …

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