An elementary fallacy

More and more middle aged and old folks are living with multiple chronic conditions, says NBC News. In fact the headline reads, "We're getting sicker."

That would seem to be really bad news. I thought modern medical science was making the world healthier, at least in the U S of A. Yet the story tells us:

The report said that in 2010, 21.3 percent of women and 20.1 percent of men between ages 45 and 64 had at least two chronic health conditions. In 2000, the rate among men was 15.2 percent, and among women it was 16.9 percent. Increases were also seen in adults older than 65, with 49 percent of men and 42.5 percent of women reporting in 2010 that they had at least two chronic health conditions. In 2000, the rates were 39.2 percent of men and 35.8 percent of women.  . . .

The increases were due mainly to rises in three conditions: hypertension, diabetes and cancer, according to the report. These increases may be due to more new cases, or due to people living longer with the conditions because of advances in medical treatments. 

Could be, could be. Or maybe something else?

The report is based on data gathered during the National Health Interview Survey, in which participants complete a detailed questionnaire about their health status and health-related behaviors. Participants reported whether a physician has diagnosed them with any of nine chronic health conditions: hypertension, heart disease, diabetes, cancer, stroke, chronic bronchitis, emphysema, current asthma and kidney disease. 

My emphasis. Guess what else happened between 2000 and 2010? The definition of diabetes and hypertension were both changed to include more people; and more and more people were screened by mammography, PSA, colonoscopy and pap smears. Hence more and more people can report that a physician has diagnosed them with one the three chronic health conditions that drive these results. Are we actually sicker? That's a completely different question.