Annals of Internal Medicine tip sheet for March 18, 2008, issue

3. New Study: Large Number of Older Adults Have Some Loss of Memory and Thinking but Not Dementia

A new study of 856 people age 71 years and older found that 22 percent had some cognitive impairment that did not reach the threshold for dementia (Article, p. 427). Each year, about 8 percent of individuals with cognitive impairment but not dementia at baseline died and about 12 percent progressed to dementia. Using the 22 percent figure, researchers calculate that in 2002 in the United States, 5.4 million people aged 71 and older had cognitive impairment without dementia. Previous estimates of cognitive impairment without dementia ranged from 5 percent to 29 percent.

4. Current Guidelines for Colonoscopy after Removal of Polyps Do not Predict Subsequent Development of Large, Advanced Polyps

Current guidelines call for follow-up colonoscopy after polyp removal based on the number, type, and size of polyps removed (Article, p. 419). For example, after removal of a polyp that is about one centimeter in size or three polyps of any size, guidelines recommend that patients have follow-up colonoscopy in three years, while those with smaller and/or fewer polyps are recommended to get a follow-up colonoscopy in five to 10 years.

An analysis of 1,905 people who had colorectal polyps removed found that this risk stratification scheme did not predict development of advanced polyps, which are considered most likely to advance to colorectal cancer.

The researchers note that colonoscopy already constitutes about 34 percent of procedures performed in the United States, and overuse can affect scarce health resources.

Editorial writers say the issue of follow-up colonoscopy is complicated by that fact that little is known about the natural history of the large polyp to understand which ones grow into cancer, that future guidelines should consider clinical factors such as cigarette smoking, waist circumference and insulin resistance in determining high risk screening categories, and finally, that for some patients, even a small 5 percent risk for developing advanced polyps is too high not to have early and frequent follow-up colonoscopies (Editorial. 477).

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