PEDIATRICS Vol. 106 No. 1 July 2000, p. e5
Received Jul 28, 1999; accepted Feb 7, 2000.
,
From the * Bureau of Reproductive and Child Health, Laboratory
Centre for Disease Control, Ottawa, Canada;
Perinatal Epidemiology
Research Unit, Departments of Obstetrics and Gynecology and Pediatrics,
Dalhousie University, Halifax, Canada; and § Departments of Pediatrics
and Epidemiology and Biostatistics, McGill University Faculty of
Medicine, Montreal, Canada.
Objective. To examine whether the magnitude of improvement in the health status of a population over time is dependent on the previous health status of that population.
Design and Setting. A study of infant mortality rates in Canada's 12 provinces and territories between the periods 1961-1965 and 1991-1995, and of infant mortality rates in 133 countries between 1960 and 1995.
Main Outcome Measures. Spearman's rank correlations, relative risks, and risk differences to measure the relationship between infant mortality in the 1960s and changes in infant mortality between the 1960s and 1990s.
Results. In Canada, regional rankings based on infant
mortality rates in 1961-1965 were strongly correlated (inversely) with
rankings based on the percent change in infant mortality between
1961-1965 and 1991-1995 (correlation coefficient =
.85). In
contrast, internationally, rankings based on infant mortality rates in
133 countries in 1960 were positively correlated with percent change
between 1960 and 1995 (correlation coefficient = .56). Regional
differences in infant mortality rates, measured using relative risks,
declined in Canada (highest relative risk: 4.2, compared with Ontario
in the 1960s; highest relative risk: 2.2, compared with Ontario in the
1990s) but increased globally (highest relative risk: 5.0, compared
with industrialized countries in 1960; highest relative risk: 15.1, compared with industrialized countries in 1995).
Conclusions. Canadian regions with higher infant mortality rates in 1961-1965 achieved larger improvements compared with regions with initially lower infant mortality rates. The pattern observed within Canada is unlike the pattern observed internationally. Key words: infant mortality, Canada, health status, industrialized countries, international.