India, June 9 -- Every day, people are exhorted to undergo "preventive" health check-ups. These come in the form of executive check-ups, prevention "camps", and bundled packs which promise more tests for less money. While many tests are good barometers of health and help modify diet and lifestyle, many others are unnecessary. Some, such as the treadmill exercise test, may even be harmful. What is wrong with having a preventive check-up? After all, wouldn't it be better to identify problems before they become serious? The answer to this question rests on two fundamental requirements. First, the ability of the test to identify individuals who are truly at risk of health problems in the future. And second, the availability of proven treatmen...