The effect of recall on estimation of incidence rates for injury in Ghana.

BACKGROUND Injury is a major public health problem in many developing countries. Due to limitations of vital registry and health service data, surveys are an important tool to obtain information about injury in these countries. The value of such surveys can be limited by incomplete recall. The most appropriate recall period to use in surveys on injury in developing countries has not been well addressed. METHODS A household survey of injury in Ghana was conducted. Estimated annual non-fatal injury incidence rates were calculated for 12 recall periods (1-12 months prior to the interview, with each successively longer period including the preceding shorter periods). RESULTS There was a notable decline in the estimated rate from 27.6 per 100 per year for a one-month recall period to 7.6 per 100 per year for a 12-month recall period (72% decline). The extent of this decline was not influenced by age, gender, rural versus urban location, nor by type of respondent (in-person versus proxy). Rate of decline was influenced by severity of injury. Injuries resulting in <7 days of disability showed an 86% decline in estimated rates from a one-month to a 12-month recall period, whereas injuries resulting in > or =30 days of disability showed minimal decline. CONCLUSIONS In this setting, longer recall periods significantly underestimate the injury rate compared to shorter recall periods. Shorter recall periods (1-3 months) should be used when calculating the overall non-fatal injury incidence rate. However, longer recall periods (12 months) may be safely used to obtain information on the more severe, but less frequent, injuries.