The Effect of Patient and Visit Characteristics on Diagnosis of Depression in Primary Care

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Original Research

The Effect of Patient and Visit Characteristics on Diagnosis of Depression in Primary Care

J Fam Pract. 2001 December;50(12):1068

References

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Results

Of the 17,058 visits made by adults to primary care physicians included in the 1997-1998 NAMCS samples, 358 visits included a diagnosis of depression Table 1. Therefore, using the weights provided by the NCHS, we estimated there were 20.2 million office visits to primary care physicians with a recorded diagnosis of depression in 1997 and 1998. This represented 2.4% of all visits to primary care physicians. The rate at which depression was diagnosed, however, varied significantly by several patient and visit characteristics, according to results from the multivariate analysis.

As we postulated, the data in Table 2 indicate that the probability of a diagnosis of depression’s being recorded during an office visit is significantly related to the patient’s reason for the visit, with depression being diagnosed over 40 times more often during visits where the patient reported depression as a reason for the visit. Also, a depression diagnosis was 3.4 times more likely to be recorded if the patient reported physical symptoms of depression as a reason for the visit and 4.9 times more likely if the patient reported other psychiatric symptoms associated with depression as a reason for the visit. However, even after controlling for the reasons for the visit, significant differences in the rate of depression diagnoses were observed by age, gender, and duration of the visit. Primary care physicians were 56% less likely to diagnose depression during visits made by elderly patients. Depression diagnoses were recorded more frequently during visits made by women, even after controlling for the patient’s reasons for the visit. Although the results are not reported in Table 2, we also questioned whether significant interactions of age with sex, race, or ethnicity were evident. We found a significant interaction of age and sex, demonstrating that elderly women were less likely to be considered depressed than elderly men (P=.01). Duration of the visit was also significantly associated with the rate at which depression diagnoses were recorded, with such diagnoses being recorded 1% more often for each additional minute that an office visit lasts. Visits during which a diagnosis of depression was recorded averaged 19.3 minutes, compared with 16.4 minutes for visits in which this diagnosis was not reported.

Differences in the rate at which depressive diagnoses were recorded were also observed by race and type of insurance coverage, although these differences did not achieve statistical significance at the P less than .05 level. A diagnosis of depression was recorded 37% (P=.055) less often during visits by African Americans and 35% (P=.08) less often during visits by Medicaid patients. After controlling for age, a diagnosis of depression was recorded 35% (P=.07) more often during visits by Medicare patients than with patients with private insurance. Large differences in rates at which a depression diagnosis was recorded were also observed by physician specialty. Family practice and general practice physicians were 65% (P <.001) more likely to record a diagnosis of depression than internists. Similar results were observed in the sensitivity analysis performed only on visits with 1 or 2 recorded diagnoses.

Discussion

Given that the prevalence of depression in epidemiologic studies is reported to approximate 12% to 18% in primary care practice,^22,23 one would expect to see a depression diagnosis recorded more frequently than in 2.4% of office visits. Admittedly, depressed patients are likely to see their physicians for reasons other than their depression and may therefore not receive a depression diagnosis during each visit. Although reporting of depressive symptoms as the reason for the visit was an important determinant of whether or not a diagnosis of depression was recorded by the physician, there were several other nonclinical factors that predicted a depression diagnosis during visits to primary care physicians.

These findings show that the rate at which diagnoses of depression are recorded during office visits is influenced by factors other than symptom presentation. Sex and age were significantly associated with a depression diagnosis. Although the prevalence of depression is higher among women,¹⁴ the likelihood that a depression diagnosis was recorded should not have varied greatly by sex after controlling for the patient’s reason for the visit. Yet, this was the case. If a man and a woman both present to a primary care physician with the same symptoms, we found that a diagnosis of depression was more likely to be recorded during the visit made by a woman. Similarly, it appears that a diagnosis of depression was less likely to be recorded during visits made by older patients. During office visits by older persons, primary care physicians may simply attribute depressive symptoms to physical ailments or the normal aging process. However, it is also possible that older patients are more likely to report depressive symptoms that are actually due to other ailments than are younger patients.