Effect of recall on estimation of non-fatal injury rates: a community based study in Tanzania

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Author(s): Moshiro C, Heuch I, Åstrøm A N, Setel P, Kvåle G

Year: 2005

Inj Prev 2005. 11:48-52.
Injuries are becoming a major cause of mortality and morbidity in less developed countries. The relative contribution of injuries to disability adjusted life years is expected to rise from 15% in 1990 to 20% in 2020 with the largest increase expected to occur in sub-Saharan Africa. Most studies on the incidence of injuries are based on health facility data. Self reported data obtained through community based surveys play an important part in the study of injury morbidity in less developed countries due to incompleteness and low utilisation of health facilities. However, one major limitation of such studies is recall bias.

A number of studies have investigated the effect of recall period on the estimates of injury rates for non-occupational and occupational injuries. A study in the United States examined the effect of recall in estimating injury rates among children and adolescents with a reference period of 12 months. The largest declines in injury rates were observed for the 0–4 year old children and for minor injuries. Similarly, Mock et al investigated the effect of recall bias on annual injury rates in a household survey in Ghana. They found a remarkable decline in injury rates from a one month recall to a 12 month recall, which was influenced by severity of injury but not by age, gender, and locality. A population based study in Brazil compared retrospective and prospective data collection methods among preschool children. Use of diaries prospectively resulted in five times as many injuries reported than the recall method, particularly for injuries not requiring medical care. In the United States, injury rates for farmers were compared using two months’, 12 months’, and 10 years’ recall. The results showed that a recall period of more than two months was likely to underestimate injury rates. Most of the studies on effect of recall on injury rates have been conducted in developed countries. A review of literature produced only one study from sub-Saharan Africa on time effects in recall of injuries.

In this paper, we investigate the effect of recall on estimates of annual injury rates as an initial step in analysing data from a survey that measured injury morbidity in an urban and a rural location of Tanzania. The effects of recall are also examined for various subpopulations and by severity of injury.