Temporal trends in the incidence of intermittent claudication from 1950 to 1999

Declines in coronary disease and stroke mortality have occurred, but it remains unclear whether intermittent claudication (IC) incidence and mortality rates have changed. The authors sought to examine long-term trends for IC in the community. Cases of IC among Framingham Study participants aged >= 40 years were classified according to date of onset from the 1950s to the 1990s. IC was defined as the presence of exertional calf discomfort that was relieved with rest. Age- and sex-adjusted incidence rate ratios were estimated using log-linear Poisson regression, and 10-year survival was calculated using the Kaplan-Meier method. IC occurred in 668 participants (286 women). The age- and sex-adjusted incidence rate of IC fell from 282 per 100,000 person-years during the period 1950-1969 to 225 per 100,000 person-years in the 1990s. The decline in IC incidence across time periods was significant (p for trend = 0.01), with an initial increase in the 1970s being followed by declines of 16% in the 1980s and 18% in the 1990s. Approximately 40% of persons with IC died within 10 years of diagnosis, with no significant change occurring during the study period. IC incidence has declined since 1950, but mortality has remained high and unchanged. Factors contributing to the declining incidence of IC need clarification.