Acquaintance networks among leukemia and lymphoma patients.

A case-control study of clustering through acquaintanceship among lymphoma and leukemia patients was conducted for the years 1967 through 1972 in Orleans County, New York. Twenty lymphoma and 17 leukemia cases met criteria for inclusion in the study. Data on acquaintanceship linkage were gathered from the source cases and controls, and from their acquaintances yielding a data base of 13,409 unique individuals linked by acquaintance. Three different analyses were carried out: a statistical analysis of linkage via intermediaries of case pairs in comparison with control pairs; a computer simulation of disease transmission from selected source cases to selected targets and controls based on the acquaintance data; and a secondary attack rate type analysis. The first two types of analysis yielded statistically significant case-control differences at the .05 level. The third method also yielded a positive result but was not subject to quantitative hypothesis testing. An additional conclusion is that these epidemiologic methods for disease with long induction periods merit further study.