During the 10 years (2006–2015) NCDs and injuries accounted for about one-third of all in-hospital deaths in Tanzania. The majority of deaths due to NCDs occurred among those 15–59 years old. Similar to our findings, a study in Ethiopia reported that NCDs contribute to high proportions of mortality in hospitals [44]. The findings of this study indicate that most of the deaths due to NCD and injuries affected the young adult group and males. Similar findings have been reported elsewhere [45]. It has been described that as age increases one becomes more exposed to the risk factors for long periods until the complications develop and hence experiences the clinical syndromes of NCDs [46]. Like in our study, males accounted for most NCD deaths in studies in Brazil, Sri Lanka, and China [47–49]. Despite the observations that NCD deaths affected more males than females, several studies in Tanzania have reported that women have a higher risk of being obese than men, hence more vulnerable to several NCDs [50–52]. Overweight and obesity are major risk factors for diabetes, cardio-circulatory diseases, and cancer [54]. A recent systematic review has identified several factors related to gender differences in the burden of NCDs. These include gender roles, physical access to recreational facilities, and preferences for walking and engaging in physical activity [55].
Cardio-circulatory diseases were the number one leading NCD cause of deaths followed by cancer and chronic respiratory diseases. Like elsewhere in Sub-Saharan Africa, the findings of this study indicate that the largest proportion of the NCD mortalities are due to cardio-circulatory diseases, cancers, chronic respiratory diseases, injuries, and diabetes [17, 21, 56, 57]. Both cardio-circulatory diseases, cancers, and chronic respiratory diseases have also been described as among the most prevalent NCDs in Tanzania [58]. According to WHO estimates, cardio-circulatory diseases are responsible for 13% of the total deaths in Tanzania [5, 21]. There has been an increased prevalence of cardio-circulatory death rates from 9–13% between 2012 and 2016 in Tanzania [5, 59]. Like in this study, previous studies in Tanzania have reported cardio-circulatory diseases as among the major causes of deaths due to NCDs [60].
The findings from this study have shown that both injuries have increased by about 63% during 10 years. The majority of the injuries in this study were associated with road traffic accidents, drowning, and animal bites. Road traffic injuries (RTI) have been reported to account for the largest proportion of unintentional injuries in low-and middle-income countries [61]. The overall 31.98/100,000 age-standardized mortality rate due to injuries in this study was similar to that reported in a population-based study in a rural district of Tanzania [39]. It has already been reported that more males than females are likely to die from injuries than women [39]. A previous descriptive analysis of road traffic injuries in Tanzania has shown that between 1990 and 2000 the number of RTI rose by 44% and that of death by 64% [32]. Globally, each year 5.1 million people die from injuries and a quarter of these deaths are due to road traffic accidents [5] and 90% occur in low- and middle-income countries [62].
An increasing trend in ASMR due to cancers and diabetes was observed throughout the 10 years. Recent estimates in Tanzania indicate that age-standardized in-hospital mortality rate for cancer is 47.8/ 100,000 population; with cervical, oesophageal, and liver cancers being among the top three causes of deaths in Tanzania [63]. Cancer has been described as a major emerging public health problem in Sub-Saharan Africa because of population aging and growth, as well as increased prevalence of key risk factors, including those associated with socio-economic transition [64]. Diabetes was also among the five leading causes of deaths due to NCDs in Tanzania. World Health Organization's recent statistics indicate diabetes mellitus death in Tanzania accounts for 1.86% of total death and age-adjusted death rate is 30.24 per 100,000 populations [8] which is higher than the findings from this study (17.21 per 100,000). As in our study where about 50% of the deaths due to diabetes affect the 15–49 years’ age group, about three-quarters of diabetes-related deaths occur in economically-productive persons under the age of 6o years [8].
Except for diabetes, the contributions of NCDs to the total deaths varied by geographical zones of the country and levels of hospitals. Chronic respiratory diseases accounted for about one-third of deaths in the Southern Western, Southern Highlands, and Central Zones. About half of all deaths due to cardio-circulatory diseases were reported from hospitals in the Southern, Lake Victoria, Western and Central zones. Eastern, Lake Victoria, and northern zones reported the largest proportion of deaths due to cancers. Injuries accounted for the largest proportions of deaths in the Western, Central, and Southern Highlands. These variations are likely to indicate regional and demographic differences in NCD prevalence underlying differences in lifestyle, socioeconomic status, and access to healthcare [65].
This study is likely to have some limitations. We analysed data on broadly defined disease categories such as chronic respiratory diseases, cardio-circulatory diseases, cancers, injuries, diabetes, brain disorders, and kidney diseases. The analysis could not make inferences on specific diseases. Moreover, despite the usefulness of the information that is available from this study, the hospital data are likely to provide an incomplete picture of the burden of NCDs in Tanzania, as the majority of deaths occur in the community and their causes are not registered. Despite these limitations, this study consolidates information on the NCD mortality and highlights patterns and trends of major NCDs in Tanzania.