The technical definition of a chronic health condition is "a physical or mental health condition that lasts more than one year and causes functional restrictions or requires ongoing monitoring or treatment." I sometimes define it a bit more loosely as a condition where the symptoms can remain at least somewhat and sometimes quite substantially under control, with appropriate behavior, treatment and monitoring, but where a short-term lapse in behavior, treatment and monitoring can lead to substantial costs, both from the health care system and for the patient's health. Christine Buttorff, Teague Ruder, Melissa Bauman offer some useful background in the chartbook, "Multiple Chronic Conditions in the United States" (RAND Corporation, May 2017).
Here's the share of US adults who have a certain prominent chronic condition. The four most common are hypertension, lipid disorders (like high cholesterol), mood disorders, and diabetes.
Of course, chronic conditions are complicated by the fact that many people have more than one of them: indeed, 12% of US adults have five or more chronic conditions.
Unsurprisingly, those who have more chronic conditions tend to have higher health care costs, emergency department visits, inpatient and outpatient stays, and use of prescription medication. Indeed, those with three or more chronic conditions account for 61% of total health care spending.
a list from the Mayo Clinic of ways of controlling high blood pressure without medication. A friend of mind had a back-pain problem severe enough that he would sometimes have to lay down on the floor in the middle of meeting, rather than keep sitting or standing. In his day-to-day struggles with back pain, one of the most important items was an appropriate mattress. To put it another way, society could address his back pain with medication or a good mattress--and the health care system tends to prioritize the first approach.
Of course, a number of health care providers do have programs to try to hold down costs by encouraging nonmedical ways of addressing chronic conditions, and some of these programs are clearly successful. But I suspect that a substantial expansion in the nonmedical aspects of dealing with chronic conditions would have a high payoff, both in reduced health care costs and in improved health.