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I-Min Lee, MBBS, ScD
Harvard School of Public Health Boston, Mass

Ralph S. Paffenbarger, Jr, MD, DrPH
Stanford University School of Medicine Stanford, Calif

JAMA. 1995;274(14):1132-1133.

	Since this article does not have an abstract, we have provided the first 150 words of the full text PDF and any section headings.

In Reply.

—Drs Pahor and Carbonin query our use of different classification criteria in analysis of physical activity and longevity in a cohort of Harvard alumni. We used three schemes for categorizing physical activity: (1) increments of 2100 kJ/wk; (2) quintiles of total energy expenditures (<2524, 2524 to <4738, 4738 to <8001, 8001 to <13142, and >13142 kJ/wk), and (3) five categories each of vigorous and nonvigorous energy expenditure, using identical cutoffs (<630, 630 to <1680, 1680 to <3150, 3150 to <6300, and >6300 kJ/wk). Since vigorous and nonvigorous energy expenditure add up to total energy expenditure, the cutoffs for category 3 are, of course, lower than those for category 2.

Ideally, we would have used category 1 for all analyses; however, using increments of 2100 kJ/wk led to small numbers of deaths (<50) within some categories (Table 2). Thus, for age-adjusted analysis, stable estimates for mortality rates could be . . . [Full Text PDF of this Article]

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