Measuring adult mortality from mobile phone surveys in Burkina Faso, Malawi and the Democratic Republic of the Congo

In many low and middle-income countries, adult mortality estimates are derived from surveys and censuses conducted through face-to-face interviews. These interviews can be time-intensive and are often impractical during health crises or humanitarian emergencies. The expansion in cellphone ownership and network coverage has created new opportunities for collecting demographic data through mobile phone surveys, but our understanding of selection biases and reporting errors of such data remains incomplete. This study reports on adult mortality estimates obtained through mobile phone surveys conducted in Burkina Faso, Malawi, and the Democratic Republic of the Congo in 2021 and 2022. To mitigate respondent fatigue and network interruptions, we used a shortened version of the set of questions generally used in surveys to ask about the survival of respondents siblings. We found substantial differences between mortality estimates obtained from mobile phone interviews and those from face-to-face demographic surveys. Mortality rates from the mobile phone surveys were also approximately half those expected from United Nations estimates. We attribute this underestimation to inaccuracies in reporting of ages and the timing of sibling deaths in the shortened sibling instrument. After imputing ages and dates based on full sibling histories collected in previous face-to-face surveys, mortality rates were more consistent with other data sources. Mobile phone surveys are promising for the measurement of adult mortality in settings where face-to-face surveys are hindered, but they are susceptible to reporting errors. More research is needed on the best set of questions to use for capturing recent adult deaths.