A new method to determine mean adult height from incomplete follow-up data

In long-term growth studies with adult height (AH) as outcome, reporting is often required while data are incomplete because some participants have not yet reached AH whereas others might be lost to follow-up. Current practice is to analyze only participants who did reach AH, which can easily give biased results. We introduce a new method into the area of growth research.

We used the data of patients from a registration database and a growth study. The new method uses growth data in time intervals. The percentage of children still growing and the mean growth at each interval are used to determine mean AH.

With the new method, estimated mean AHs had smaller bias and standard error than with commonly used methods. The method is not hampered by a correlation between AH and age at reaching AH, unlike methods merely using patients who have reached AH.

In contrast to commonly used methods, the new method provides valid results on mean AH when complete actual measurements of AH are not (yet) available, provided that drop-out, if any, is not related to (disappointing) growth. As it also uses observed data of children with incomplete follow-up, the method employs the data more effectively.