Metodología para la detección le vulnerabilidades en la red de datos

Under 28 weeks (under 196 days), 28-31 weeks (196-223 days), 32-36 weeks (224-258 days), 37-41 weeks (259-293 days), 42 weeks and over (294 days and over).

5.8

Standards and reporting requirements related to maternal mortality

5.8.1 Definitions

Maternal death

A maternal death is the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the duration and the site of the pregnancy, from any cause related to or aggravated by the pregnancy or its management, but not from accidental or incidental causes.

Late maternal death

A late maternal death is the death of a woman from direct or indirect obstetric causes more than 42 days but less than one year after termination of pregnancy.

Pregnancy-related death

A pregnancy-related death is the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the cause of death.

Maternal deaths should be subdivided into two groups:

Direct obstetric deaths: those resulting from obstetric complications of the pregnant state (pregnancy, labour and puerperium), from interventions, omissions, incorrect treatment, or from a chain of events resulting from any of the above.

Indirect obstetric deaths: those resulting from previous existing disease or disease that developed during pregnancy and which was not due to direct obstetric causes, but which was aggravated by physiologic effects of pregnancy.

In order to improve the quality of maternal mortality data and provide alternative methods of collecting data on deaths during pregnancy or related to it, as well as to encourage the recording of deaths from obstetric causes occurring more than 42 days following termination of pregnancy, the Forty-third World Health Assembly in 1990 adopted the recommendation that countries consider the inclusion on death certificates of questions regarding current pregnancy and pregnancy within one year preceding death.

5.8.2 International reporting

For the purpose of the international reporting of maternal mortality, only those maternal deaths occurring before the end of the 42-day reference period should be included in the calculation of the various ratios and rates, although the recording of later deaths is useful for national analytical purposes.

5.8.3 Published maternal mortality rates

Published maternal mortality rates should always specify the numerator (number of recorded maternal deaths), which can be given as:

• the number of recorded direct obstetric deaths, or

• the number of recorded obstetric deaths (direct plus indirect).

It should be noted that maternal deaths from HIV disease (B20-B24) and obstetrical tetanus (A34) are coded to Chapter I. Care must be taken to include such cases in the maternal mortality rate.

5.8.4 Denominators for maternal mortality

The denominator used for calculating maternal mortality should be specified as either the number of live births or the number of total births (live births plus fetal deaths). Where both denominators are available, a calculation should be published for each.

Ratios and rates

Results should be expressed as a ratio of the numerator to the denominator, multiplied by k (where k may be 1000, 10 000 or 100 000, as preferred and indicated by the country). Maternal mortality ratios and rates can thus be expressed as follows:

Maternal mortality rate1

Maternal deaths (direct and indirect) x k

Live births

Direct obstetric mortality ratio

Direct obstetric deaths only x k

Live births

Pregnancy-related mortality ratio

Pregnancy-related deaths x k

Live births

5.9

Proportion of deaths classified to ill-defined causes

The allocation of a high proportion of causes of death to Chapter XVIII (Symptoms, signs, and abnormal clinical and laboratory findings, not elsewhere classified) indicates a need to check or estimate the quality of the tabulated data allocated to more specific causes assigned to other chapters.

5.10 Morbidity

There are a wide variety of possible sources of information on morbidity. The data most suitable for analysis on a national or regional basis are those that enable some calculation to be made of the incidence of diseases, or at least of those diseases coming, for example, under medical or hospital care. It is primarily for data on episodes of health care that the formally agreed guidelines and definitions for recording causes of morbidity and selection of a single condition, where appropriate, are intended. Other types of data require the development of local rules.

The problems of morbidity statistics start with the very definition of “morbidity”. There is much scope for improving morbidity statistics. International comparisons of morbidity data are, at present, feasible only to a very limited extent and for clearly defined purposes. National or regional information on morbidity has to be interpreted in relation to its source and with background knowledge of the quality of the data, diagnostic reliability, and demographic and socioeconomic characteristics.

5.11 Precautions needed when tabulation lists include subtotals

It may not always be apparent to those processing the data that some of the items in the tabulation lists are in fact subtotals; for instance, titles of blocks and, in the case of the four-character list of ICD-10, titles of three-character categories, as well as the items for chapter titles in the condensed versions of the mortality tabulation lists. These entries should be ignored when totals are calculated, otherwise cases would be counted more than once.

5.12 Problems of a small population

Population size is one of the factors that has to be considered when the health status of a population is assessed by means of mortality or morbidity data. In countries with small populations, the annual numbers of events in many categories of the short lists will be very small, and will fluctuate randomly from year to year. This is especially so for separate age groups and sexes. The problems can be alleviated by one or more of the following measures:

• use or presentation of broad groupings of ICD rubrics, such as chapters;

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• aggregation of data over a longer period, e.g. to take the preceding two years’ data together with those for the current year and produce a “moving average” figure;

• using the broadest of the age groupings recommended at 5.6.1 and 5.7.4.

What applies for small national populations also holds true in general for subnational segments of larger populations. Investigations of health issues in population subgroups have to take into consideration the effect of the size of each of the subgroups on the type of analysis used. This need is generally recognized when dealing with sample surveys, but often overlooked when the investigation concerns the health problems of special groups in the national population.