The NHWS data revealed that patients' primary care physicians, general practitioners, and internists diagnose depression slightly more often for people with arthritis and migraines than for the depressed population in general. Such doctors diagonse depression 44 percent of the time for all depressed patients, and 49 percent of the time for arthritis and migraine patients. Psychiatrists made the depression diagnosis about a third of the time across all three categories of patients. So patient pain does not impair physicians' ability to spot co-morbid depression (other than perhaps in the elderly, as discussed previously).

In fact, based on a comparison of self-reported cases of depression and diagnosed cases of depression, patients diagnosed with either arthritis or migraines actually stand a better chance than the population in general of having a physician diagnose their depression. Among respondents self-reporting depression, 28 percent say their condition has not been diagnosed, compared to 14 percent of people with arthritis or migraines along and depression, and 17 percent with high cholesterol and depression. Reporting a painful ailment to a doctor increases the likelihood that co-morbid depression will be noticed. Painful ailments do not obscure the mood disorder, at least when all patient ages are taken together.

What is more, a depression diagnosis leads to treatment somewhat more often for people with a painful physical condition than in the general, depressed patient population. And, for people with arthritis, the depression treatment is a little more likely to be a prescription medication.

How much does treating depression mater to the treatment of arthritis or migraine? Does treating co-morbid depression in arthritis and migraine patients enable patients to function at a different level? Are their health outcomes significantly improved on both the mental and physical front? How does the type of depression treatment make a difference?

It is possible to shed light on this by comparing "SF 8" scores across patients in both diseases, broken out by the type of depression treatment they receive (none, Rx, OTC, or Rx and OTC in combination). (Short Form 8 scores are a multi-purpose, generic measure of health status developed by Quality Metric that consists of eight questions designed to assess physical functioning, role limitations due to physical health problems, bodily pain, general health, vitality, social functioning, role limitations due to emotional problems, and mental health. A score of 50 is the norm.)

NHWS data confirm the fact that the presence of depression significantly impacts the mental and physical SF 8 scores for both arthritis and migraine patients. The mental SF 8 score for arthritis patients without co-existing depression is 51, and 40 for those with undiagnosed depression. For migraine sufferers, the presence of untreated depression pulls the mental SF 8 score down from 48 to 38. In both cases, the physical score drops two points with the presence of untreated depression.

Patients whose symptoms are severe enough to be receiving a prescription medication for their depression have even lower scores. Unfortunately, we don't know how low their scores were before they began depression treatment, only that even in treatment they remain markedly more limited than their counterparts without depression. It is important to note that this particular analysis did not take into account the type of concomitant treatment that patients may or may not receive for their arthritis or migraine (although this variable could easily be factored in).

Curiously, arthritis and migraine patients treating their depression with an OTC product score the highest of any of the depressed groups in the physical SF 8 score. This suggests that their symptoms may not have been as severe to begin with.

Pain and depression may be forever inextricably linked, but with proper diagnosis and treatment, the two conditions will not launch a downward spiral of greater suffering. The same is true of other co-morbid conditions. By sharing information on the incidence, symptoms, and treatment outcomes of people suffering more than one affliction at once, the pharmaceutical industry can work with healthcare providers to improve the quality of life for millions of Americans.

Michael Fronstin is vice president of sales for Consumer Health Sciences, which produces the National Health and Wellness Survey. He can be reached at michael.fronstin@chsinternational.com