This study sought to identify the causes of death in our study area based on the verbal autopsy technique. Variability in recall period, a frequently cited limitation of VA is reported in our study. The median time was 8 months, about double that reported in other studies [14
]. This is due to the data collection period used in our study that was only twice a year during the first six years of the study. However despite this limitation, interviews well recorded the signs and symptoms presented during the illness period preceding death. Other possible limitations included the relatively low specificity and sensitivity of the VA tool for detecting major causes of childhood death and the need to validate the diagnosis. In validation studies conducted in Maputo in children under 5 years old, verbal autopsy was judged to be appropriate to detect measles (sensitivities 75%, specificity 98,6%), ALRI (sensitivities, 66,7%, specificity 85,4%) and malaria (sensitivities 62,8%, specificity 90,3%) but it performed poorly for meningitis (sensitivities 33,3%, specificity 98,6%) and anaemia (sensitivities 51,9%, specificity 84,9%)[15
]. These results are comparable with the results of other validation studies made in Africa, including reported by Snow et al [3
], Chandramohan et al [5
], Kahn et al [16
] and Philip WS et al [17
Whether to use a single or a multiple diagnostic cause is arguable particularly in the regions where patients present more than one pathology [4
], as it was observed in the current study. A single diagnosis of cause of death can be used, with the assumption that other causes are ignored in the analysis. An alternative type of analysis when more than one cause of death is considered has been described by Adjuik et al [18
]. He has allocated percentages of a death to the codes assigned, in proportion to the number of coders who offered a diagnosis. This methodology may underestimate individual rates per cause. For us, many times it is difficult to assign a single cause of death because the process that leads to death is complex and several diseases are involved. We try to solve this question giving the same weight for each cause of death. However it is possible that our methodology may overestimate the individual rates per cause.
In our study about 54% of all deaths took place outside a health facility. This percentage is slightly lower than that found in another study carried out in Manhiça district between 1994–96 (59,9%) [19
], and is a strong reminder that access to the health facilities is not just a matter of distance, as other factors may be even more important in defining the pattern of health seeking behaviour in the area. Even when taking into account all the limitations described above, the tool may be useful in monitoring changes in mortality patterns over time.
In children under 15 years of age, mortality decreased about 30% during the last 5 years in the Manhiça study area, but the same decrease has not been observed in adults (Nhacolo A, unpublished). A main factor not only in Mozambique but in other neighbouring countries is the rapid growth of AIDS cases in adults [9
The crude mortality rates found in this study are similar to those reported by Adjuik M, for sites as Africa Center (ACDIS) in South Africa (16.5/1000 pyrs) and Navrongo in Ghana(15.6/1000 pyrs) [18
] and by Korenromp EL, for sites in Hai district (16.6/1000 pyrs) and Dar es Salam (26/1000 pyr) in Tanzania [20
]. The Manhiça study area has a similar mortality pattern and high rate of deaths due to infectious disease as other African countries. The pattern of child deaths found in Manhiça is typical of developing countries [21
Malaria due to Plasmodium falciparum
was the main killer among children between 28 days to 4 years living in Manhiça area. Overall, one in four deaths was due to malaria infection. The spread of resistance to antimalarial drugs, especially chloroquine, has probably contributed substantially to this increase before 2001. After 2001, malaria cases and malaria mortality rapidly declined in the study area [23
]. This may be due to several reasons such as use of more effective antimalarial drugs for treatment of non severe malaria cases such as sulfadoxine-pyrimethamine (SP) plus chloroquine initially in 2000 and SP plus amodiaquine that began in 2002. In addition, intervention studies including a malaria vaccine candidate trial for children aged 1 to 4 years, [24
] or an the intermittent preventive treatment trial in infants using SP [27
] and the distribution bed nets to pregnant mother during the last 5 years may be contributed to drop in the malaria death rate.
Pneumonia was the second overall largest cause of death in children, and was the first cause in the neonatal group. This finding is not surprising [28
] and highlights the importance of some pathogens, particularly the Streptococcus pneumoniae
and Haemophilus Influenzae
, as major health threats to African children. The observed age pattern of pneumonia deaths, whereby neonatal infants experience the highest burden, is confirmed by morbidity data from this area [8
]. The specific death rates decreased after 2002, particularly in children less than 5 years, when surveillance of pneumococcal disease was established.
The high ranking of HIV/AIDS in children between 29 days and 1 year explained by the growing HIV epidemic in the study area. Many HIV/AIDS deaths were probably related to malnutrition, pneumonia, malaria and diarrhoea. Given the 23.6% HIV maternal seroprevalence detected at the antenatal clinics between August 2003 and April 2005 (Menendez C – in press), we might have expected more deaths from AIDS than the reported 8.3%. It is probable that many deaths registered as diarrhoeal disease and malnutrition also had AIDS as the underlying cause, but was not reported as such. The crude death rate began decreasing later 2004, just after the implementation of antiretroviral treatment in MDH.
Diarrhoea related deaths accounted for 8% of all deaths and remains as another main contributor to child mortality in Manhiça. A similar results has been reported by Dgedge et al in children from 0 to 14 years of age in Maputo City where up to 10% of paediatric deaths are attributed to diarrhoeal [21
]. In sub-Saharan Africa, hospital-based mortality from acute diarrhoea varies from 1.9% of all deaths in The Gambia to 37% in Nigeria, with most of deaths occurring during the first year of life [30
]. Even though morbidity caused by diarrhoea is still high, mortality has been decreasing worldwide, also in Manhiça, mainly because of improved management and community education [31
Malnutrition constitutes an important cause of child death in Africa [34
]. In Manhiça the specific rate decreased during the study period due to an effective malnutrition programme in MDH that included improved detection, treatment and community follow-up at home of children after discharge from hospital. However several other factors such as poor socio-economic conditions, increasing prevalence of HIV/AIDS and tuberculosis, and the migration of the adult male population to Maputo capital and South Africa [9
] may have all contributed to maintaining a high prevalence of this disease in the study area.
In Manhiça the crude mortality rate for diarrhoeal diseases, decreased at the same pace as malaria and malnutrition deaths. These related patterns suggest the relationship and possible misclassification of cause of death among these three diseases.
Finally, these results confirm that most causes of death in children are preventable. Research and programs that enable mothers to identify malaria, acute respiratory infections (particularly pneumonia) and diarrhoea, and that encourage prompt care-seeking behaviour. Strengthening case management at the primary health care facilities are important priorities. Morbidity and mortality related to prenatal causes, including asphyxia, can be reduced if staff is well-trained. Mothers should be encouraged to seek early for antepartum and intrapartum care for adequate attendance. The quality of neonatal care, with a focus on preventing infection needs to be improved.