versión impresa ISSN 0042-9686
Bull World Health Organ vol.86 no.3 Genebra mar. 2008
The usual words of caution
Bulletin of the World Health Organization
The cover on the March issue of the Bulletin, the third in this year's commemorative volume, illustrates the importance of health information, a topic that has been on the World Health Assembly's agenda for the past 60 years. This month's issue includes a story on the difficulties of ensuring continuity of record keeping in times of conflict and a discussion of the merits of concentrating financial and human resources for this activity in the countries concerned rather than in global institutions. So what has changed since WHO took over the responsibility for collating national data on births, deaths and disease in 1948?
First, health statistics are in much greater demand by a wider variety of users than ever before. Second, the tools for their collection and dissemination have improved considerably. Third, there is much more debate about how to interpret these numbers and who owns them.
Every day WHO receives more than 150 enquiries from journalists, academics, students, companies and other members of the public on topics ranging from the impact of biofuels on food security to how to define the number of calories that constitute a starvation diet. Academics cite and contest WHO's numbers, ministries of health use them for planning, donors employ them to track progress on development goals, and some people request information on the performance of health systems to choose between countries as holiday or retirement destinations.
Among the ways that WHO disseminates its information is via web sites (at headquarters, regional and country offices). The first of these web sites was set up in 1996 and it now receives more than two million page views per day. WHO still prints hundreds of publications each year, most of which contain some statistical information; for example annual reports from the single-disease programmes, the Bulletin, the Weekly epidemiological record, revisions of the Global burden of disease and its annual World health statistics. WHO's information is also disseminated through international print and broadcast media. It has become increasingly complex for people to find a path through all these sources to the information they need. Both methods and results are the subject of increased scrutiny. For example, this past year alone has seen the methods used to estimate trends in child mortality, global HIV prevalence and maternal mortality contested and re-examined.13
Yet, looking back to the first of WHO's Annual epidemiological and vital statistics (19391946),4 only one of the many caveats it lists with respect to the accuracy of health statistics has been resolved in the intervening years, and it is not in the health sector. This first volume served as the continuation for the statistical series published annually by the Health Organization of the League of Nations since 1923. It included all the available country data from the war years immediately preceding WHO's establishment.
"All countries do not yet possess complete, exact and comparable statistics on their area and population. In many cases only estimates are available, sometimes very rough ones."
Luckily, this first problem, that of determining land mass, was settled by the introduction of satellite imagery in the 1960s. The outstanding issue is predicting how much of that land mass will remain arable, habitable or at least free of vector-borne diseases such as malaria in coming decades. The second problem, that of population, still holds and sounds very familiar:
"For many extensive territories, particularly in Africa and Asia, censuses, at least in so far as the indigenous population is concerned, are very often nothing more than counts carried out by various methods number of huts or cabins, number of heads of families or individuals paying taxes, etc."
Variations in the practices of certifying and coding of causes-of-death have proven to be a very tenacious problem, and the following introduction to these statistical tables has been repeated in similar words in many WHO publications:
" the usual words of caution should be uttered as regards the comparability of the different national mortality statistics compiled in this volume. It is well known that both the accuracy in diagnosing causes of death and the way in which these diagnoses appear on death certificates and are tabulated for statistical analysis still vary from one country to another, and sometimes to a considerable degree "
The above citation, written more than 60 years ago, is still valid today. It underscores the fact that the validity and reliability of statistics can always stand to be improved. Timeliness is another issue. At least in 1948 there was a good excuse. The introduction addresses reasons for delay, understandable;
" if one considers not only the task of collecting, checking, and editing a very large number of figures, but also the difficulties involved for the national administrations themselves in dealing with statistics for the war period, during which exceptional circumstances, such as invasion, occupation, bombing of cities, migration, mobilization, etc. caused serious disruption of administrative practice."
Many countries still experience exceptional circumstances and serious disruption but, without a technological alternative to the laborious compilation of a global picture from individual records, WHO's efforts to improve health information are likely to continue on the slow but steady path they have traced since its inception.
1. Murray CJL, Laakso T, Shibuya K, Hill K, Lopez AD. Can we achieve Millennium Development Goal 4? New analysis of country trends and forecasts of under-5 mortality to 2015. Lancet 2007;370:1040-54. PMID:17889243 doi:10.1016/S0140-6736(07)61478-0 [ Links ]
2. Hill K, Thomas K, AbouZahr C, Walker N, Say L, Inoue M, et al. Estimates of maternal mortality worldwide between 1990 and 2005: an assessment of available data. Lancet 2007;370:1311-9. PMID:17933645 doi:10.1016/S0140-6736(07)61572-4 [ Links ]
3. De Lay P, Garnett G. How UNAIDS makes its HIV estimates. Financial Times 1 Dec 2007. [ Links ]
4. Annual epidemiological and vital statistics 1939-1946. Geneva: WHO; 1951. [ Links ]