THE AUTHORS REPLY

Ulrike Peters1,2, Charles Poole1 and Lenore Arab1

1 Department of Epidemiology, University of North Carolina School of Public Health, Chapel Hill, NC.
2 Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD.

Drs. Thrift and Donnan (1) have pointed out that the heterogeneity among risk estimates for tea consumption and stroke, as described in our meta-analysis (2), might also be explained by differences in subtypes of stroke. To address this valid concern, we divided studies by subtypes of stroke if sufficient information was provided. For only intracerebral hemorrhage did more than one study provide an effect estimate for tea consumption. Whereas one study (3) reported an increased risk of 51 percent for an increment of three cups/day of tea consumption, the other two studies reported decreases of 7 percent (4) and 30 percent (5). The three estimates were not homogeneous (p = 0.07). Factors such as study design or geographic region might explain part of this heterogeneity. We agree that it would be helpful for studies of cardiovascular and cerebrovascular events to be more specific and more consistent in their outcome definitions.

REFERENCES

  1. Thrift AG, Donnan GA. Re: "Does tea affect cardiovascular disease? A meta-analysis." (Letter). Am J Epidemiol 2002;156:490.[Free Full Text]
  2. Peters U, Poole C, Arab L. Does tea affect cardiovascular disease? A meta-analysis. Am J Epidemiol 2001;154:495–503.[Abstract/Free Full Text]
  3. Thrift AG, McNeil JJ, Forbes A, et al. Risk factors for cerebral hemorrhage in the era of well-controlled hypertension. Melbourne Risk Factor Study (MERFS) Group. Stroke 1996;27:2020–5.[Abstract/Free Full Text]
  4. Hirvonen T, Virtamo J, Korhonen P, et al. Intake of flavonoids, carotenoids, vitamins C and E, and risk of stroke in male smokers. Stroke 2000;31:2301–6.[Abstract/Free Full Text]
  5. Sato Y, Nakatsuka H, Watanabe T, et al. Possible contribution of green tea drinking habits to the prevention of stroke. Tohoku J Exp Med 1989;157:337–43.[ISI][Medline]