The life table. A method for analyzing longitudinal studies.

The life table is presented as the method of choice for analyzing data from longitudinal studies in which the outcome under study occurs randomly and in which patients are followed up varying lengths of time. We discuss the superiority of the life table to methods typically used, the calculation of its entries, and some of the clinical uses that can be made of its results. The method is applied to follow-up data on manic-depressive patients maintained with prophylactic lithium carbonate or with control regimens, and it is shown to disclose mathematical regularities in the parameters of longitudinal course.