The Association Between Physical Activity in Leisure Time and Leukocyte Telomere Length
From: Arch Intern Med. 2008;168(2):154-158
Background Physical inactivity is an important risk factor for many aging related diseases. Leukocyte telomere dynamics (telomere length and age-dependent attrition rate) are ostensibly a biological indicator of human aging. We therefore tested the hypothesis that physical activity level in leisure time (over the past 12 months) is associated with leukocyte telomere length (LTL) in normal healthy volunteers.
Methods We studied 2401 white twin volunteers, comprising 2152 women and 249 men, with questionnaires on physical activity level, smoking status, and socioeconomic status. Leukocyte telomere length was derived from the mean terminal restriction fragment length and adjusted for age and other potential confounders.
Results Leukocyte telomere length was positively associated with increasing physical activity level in leisure time; this association remained significant after adjustment for age, sex, body mass index, smoking, socioeconomic status, and physical activity at work. The LTLs of the most active subjects were 200 nucleotides longer than those of the least active subjects. This finding was confirmed in a small group of twin pairs discordant for physical activity level (on average, the LTL of more active twins was 88 nucleotides longer than that of less active twins).
Conclusions A sedentary lifestyle (in addition to smoking, high body mass index, and low socioeconomic status) has an effect on LTL and may accelerate the aging process. This provides a powerful message that could be used by clinicians to promote the potentially antiaging effect of regular exercise.
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Variations Between Clinical Trial Participants and Medicare Beneficiaries in Evidence Used for Medicare National Coverage Decisions
Centers for Medicaid and Medicare Services often make national coverage determinations based on clinical trials among subjects whose demographics differ substantially from those of Medicare beneficiaries.
From: Arch Intern Med. 2008;168(2):136-140.
Background There is a paucity of data on the adequacy of the resources and tools used by the Centers for Medicaid and Medicare Services (CMS) in making national coverage determinations about services for beneficiaries. The objective of this study was to determine the extent to which clinical trials relied on by the CMS are applicable to Medicare beneficiaries.
Methods We performed a meta-analysis of data on 40 009 individuals from all 141 trials included in the technology assessments for the 6 cardiovascular disease meetings of the CMS advisory panel and compared them with the demographics of the Medicare population.
Results Medicare beneficiaries differ significantly from the cardiovascular clinical trial participants used to inform Medicare coverage decisions. Clinical trial participants, compared with beneficiaries, are more likely to be younger (60.1 vs 74.7 years), male (75.4% vs 41.8%), and non-US residents (60% vs 0%). The clinical trials, moreover, rarely included outcome stratification by age, sex, and race.
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