Socioeconomic status and childhood leukaemia: a review.
BACKGROUND
A long-held view links higher socioeconomic status (SES) to higher rates of childhood leukaemia. Some recent studies exhibit associations in the opposite direction.


METHODS
We reviewed journal literature through August 2002 for associations between childhood leukaemia and socioeconomic measures. We determined the direction of each association and its P-value. We described the results with regard to study design, calendar period, geographic locale, and level of the socioeconomic measures (individual or ecological). For measures with sufficient number of results, we computed summary P-values across studies.


RESULTS
Case-control studies conducted in North America since 1980 have involved subject interviews or self-administered questionnaires and have consistently reported inverse (negative) associations of childhood leukaemia with individual-level measures of family income, mother's education, and father's education. In contrast, associations have been consistently positive with father's occupational class in record-based case-control studies and with average occupational class in ecological studies.


CONCLUSIONS
Connections of SES measures to childhood leukaemia are likely to vary with place and time. Validation studies are needed to estimate SES-related selection and participation in case-control studies. Because different socioeconomic measures (such as income and education) and individual-level and ecological-level measures may represent different risk factors, we advise researchers to report these measures separately rather than in summary indices of social class.
Poole
Charles
C
Department of Epidemiology, University of North Carolina School of Public Health, Chapel Hill, 27599-7435, USA. cpoole@unc.edu
Greenland
Sander
S
Luetters
Crystal
C
Kelsey
Jennifer L
JL
Mezei
Gabor
G
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D004522:Educational Status; D006801:Humans; D007182:Income / Q000706:statistics & numerical data; D007223:Infant; D007231:Infant, Newborn; D007938:Leukemia / Q000453:epidemiology* / Q000209:etiology*; D012307:Risk Factors; D012923:Social Class