OBJECTIVES: The purpose of our study was to determine if factors other than the patient’s clinical presentation were associated with the likelihood of depression being recognized during a physician office visit.

STUDY DESIGN: We used a cross-sectional design.

POPULATION: Data from the 1997 and 1998 National Ambulatory Medical Care Surveys were examined.

OUTCOMES MEASURED: We assessed the association of factors such as age, sex, race, physician specialty, type of insurance, and visit duration with a recorded depression diagnosis during office visits to primary care physicians.

RESULTS: After controlling for symptom presentation, primary care physicians were 56% less likely to record a diagnosis of depression during visits made by elderly patients, 37% less likely to do so during visits by African Americans, and 35% less likely to do so during visits by Medicaid patients. Visits with a depression diagnosis were, on average, 2.9 minutes longer in duration (16.4 vs 19.3) than visits without a depression diagnosis. Family practice and general practice physicians were 65% more likely to record a diagnosis of depression than internists.

CONCLUSIONS: Many factors were associated with making and recording a depression diagnosis beyond the patient’s reported symptoms. If rates of diagnosis are to improve, interventions that go beyond getting physicians to recognize the symptoms of depression are needed.

KEY POINTS FOR CLINICIANS

Receipt of a recorded depression diagnosis during office visits to primary care physicians is dependent on patient age, race, and type of insurance.
Family practice and general practice physicians are more likely than internists to record a depression diagnosis during office visits.
Many factors beyond the patient’s reported symptoms are associated with making and recording a depression diagnosis.

Characteristics and Depression Diagnosis

Depression is a common disorder that significantly affects quality of life, functioning, and even mortality.^1-4 However, as indicated in the Surgeon General’s Report on Mental Health, depression remains under-recognized and underdiagnosed.⁵ Most studies examining recognition of depression have focused on the role of symptom presentation, the use of screening tools, and physician educational interventions designed to improve symptom recognition.⁶ However, factors other than clinical presentation may be associated with the likelihood that depression is recognized during a physician visit.^7,8 For example, patient age and race, type of insurance, and duration of the visit may increase or decrease the rate at which a depression diagnosis is recorded. Also, diagnostic rates may differ between family or general practice physicians and internists. If differences in diagnostic rates indeed occur because of extraclinical factors and current interventions continue to focus primarily on recognition of patients’ symptoms, certain patient groups will continue to be underdiagnosed and undertreated.

Given this concern about the range of factors possibly associated with receiving a depression diagnosis, we examined data from a nationally representative sample of office visits to physicians, the National Ambulatory Medical Care Survey. More specifically, we examined the independent role of factors such as age, sex, race, type of insurance, and duration of the visit on the probability that depression would be diagnosed during a patient’s visit to a primary care physician. Although the prevalence of depression is greater in women, there should not be a large difference in the likelihood that a depression diagnosis is recorded during an office visit after controlling for the patient’s reason for encounter. Similarly, if primary care physicians are recording diagnoses of depression based solely on the patient’s reasons for encounter, the likelihood that a depression diagnosis is recorded should be similar by age, even though there is a reported lower prevalence of major depression in elderly persons (minor depression is believed to occur more frequently in the elderly).⁹ Admittedly, however, some of the somatic symptoms associated with depression (eg, fatigue) are more likely to be due to a physical illness rather than depression in elderly patients. Thus, rates of diagnoses can should be slightly lower among elderly persons. However, because of primary care providers’ lack of confidence in assessing and diagnosing adults with depression^1,10 and the tendency for older persons to present depressive symptoms in terms of somatic complaints,^11,12 depression diagnoses are expected to be recorded much less frequently during visits by elderly persons, even after controlling for the patient’s reasons for the visit. Also, although African American patients have a lower reported prevalence and incidence rate of depression,^13,14 one would expect depression diagnoses to be recorded at rates similar to those for other races after controlling for patient presentation of symptoms. Nevertheless, cultural stereotypes among providers may lead to depression diagnoses being recorded less frequently during these visits.^15,16

With regard to practice factors affecting accurate diagnosis, since primary care physicians tend to schedule short patient visits and have many conditions to treat during those visits, we expected that the probability of a depression diagnosis being recorded would increase as the duration of the visit increased. Given competing demands for the physician’s awareness, depression often gets less attention during visits where the patient has a recent medical problem or even several of them.¹⁷ Finally, we expected family and general practice physicians to diagnose depression more often than internists. Family practice physicians express more responsibility for treating depression, tend to have more complete knowledge of available treatments, and are more confident in managing a mood disorder.¹⁰

Methods

Data

The study used data from the 1997 and 1998 National Ambulatory Medical Care Surveys (NAMCS). The NAMCS, which have been conducted every year since 1989 by the National Center for Health Statistics (NCHS), sample a nationally representative group of visits to physicians in office-based practices. The NCHS included weights in the NAMCS to enable the sample to represent all office visits in the United States. A detailed description of the NAMCS sample and sampling procedure, as well as a description of the survey instrument and survey administration procedures, is provided elsewhere.^18,19

There were 24,715 visits sampled in 1997 and 23,339 visits sampled in 1998. For each office visit, the survey provided information on physician specialty, up to 3 diagnoses, and up to 3 patient reasons for the visit. Because there were fewer than 200 visits with a diagnosis of depression sampled in each year, we combined the data from 1997 and 1998 to increase the power of the analysis. We limited our analysis to the 17,058 visits made during this interval by adults 18 years and older to primary care physicians. Primary care physicians included physicians with specialties of family practice, general practice, or internal medicine. Item nonresponse rates in the NAMCS data are low (<5%), and the NCHS provides imputed values for any missing information on demographic variables and duration of the visit in the NAMCS data.¹⁹

Diagnostic Groups

Patients were categorized on the basis of diagnoses assigned by providers during the index visit, using the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM). We classified depression visits as those with ICD-9 codes of 296.2 (major depressive disorder, single episode), 296.3 (major depressive disorder, recurrent), 300.4 (neurotic depression), 311 (depressive disorder, not elsewhere classified), and 298.0 (depressive type psychosis).

Patient and Visit Characteristics

Information on patient age, race, and ethnicity was recorded in the NAMCS survey, as was information on whether the visit was prepaid or fee-for-service and type of insurance coverage (eg, private, Medicaid, Medicare). The duration of the visit was also recorded. The survey reported physician specialty; we classified primary care physicians into 2 groups: family practice/general practice and internal medicine. The survey also indicated whether the physician had seen the patient previously. Information on up to 3 reasons for the visit, according to the patient, was collected in the survey at the time of the visit. Self-reported depressive symptoms were divided into 3 categories: (1) depressed mood, (2) physical symptoms of depression (eg, tiredness, general weakness or ill feeling, weight loss, restlessness, disturbance of sleep, abnormal appetite), and (3) other psychiatric symptoms associated with depression (eg, nervousness, fears and phobias, problems with self-esteem and identity, disturbance of memory, social adjustment problems, intentional self-mutilation, and suicidal ideation). The number of medications prescribed during the visit and the visit’s duration were recorded in the survey and used in the analysis.

Analysis

We sought to examine the role of patient and visit characteristics on the probability that a depression diagnosis was recorded during an office visit to a primary care physician. Specifically, we investigated the independent effect of factors such as age, race, sex, type of insurance, and duration of the visit on the probability of receiving a depression diagnosis, after controlling for patient-reported symptoms of depression, physician specialty, and other patient characteristics. Factors associated with having a depression diagnosis recorded were determined using weighted logistic regression models, and adjusted odds ratios and their 95% confidence intervals were calculated. Statistically significant differences in recognition rates were identified by reducing the sample weights by the proportion needed to downweight the sample to the size of a simple random sample with the same variance.²⁰ Although this method did not address problems caused by clustering within strata, it produced results that tend to overcompensate rather than undercompensate for artifacts produced from stratification.²¹ Significant differences were identified by testing the coefficients using a c2 test.

A sensitivity analysis was performed. We were concerned that patients with multiple medical conditions may be less likely to have a depression diagnosis recorded in the NAMCS because the survey only allows for 3 recorded diagnoses, and because these patients may not be randomly distributed by age, sex, race, type of physician, and so forth. A weighted logistic regression analysis was conducted on the subset of visits that recorded only 1 or 2 diagnoses (N=14,135). This should eliminate visits in which depression was recognized but a diagnosis was not recorded because 3 other conditions were perceived to be more important by the physician. The results of this analysis were then compared with results based on the full sample.

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.

African Americans were less likely to have a depression diagnosis recorded than were non-African Americans during visits to primary care physicians, even after controlling for mood disorder related symptoms. Primary care physicians possibly perceive African American patients to be stigmatized by a depression diagnosis more frequently than non-African American patients and thus choose not to assign them this diagnosis. It is also conceivable that primary care physicians do not assess physical and mood symptoms in African American patients as indicative of depression because of preconceptions about African American patients and their morbidities. The causes of racial differences in diagnosis rates cannot be determined from the NAMCS data set and warrant further study with different research strategies.

The duration of the visit had a significant effect on the probability that a depression diagnosis was recorded. Given that primary care physicians typically treat or monitor several conditions during a relatively short visit, it is not surprising that depression is recognized and diagnosed more often during longer visits. However, it may not be the case that depression was recognized because the visit was longer. It may be that visits of depressed patients just take longer. It is not possible to determine the causal relationship with this data. Again, further studies are needed of the physician diagnosis-making process.

Finally, a depression diagnosis was much more likely to be recorded during visits to family practice or general practice physicians than to internists. One may speculate that this occurs because the training of family/general practice physicians focuses more extensively on the identification and treatment of psychosocial problems than does the training of physicians who specialize in internal medicine. Only a third of training directors for internal medicine residencies were satisfied with the training received by their residents with regard to depression.²⁴ Additionally, internists are much less likely to consider themselves responsible for treatment of depression than are family physicians.¹⁰ Although it is possible that the prevalence of depression is greater among patients treated by family/general practice physicians than internists, differences in the true prevalence of depression among physician practices could not be ascertained using this data. However, controlling for patient symptoms should have accounted for much of the difference in prevalence.

Limitations

The study’s findings should be interpreted cautiously because of various limitations of the dataset. This analysis was based on a nationally representative sample of physician office visits in which a diagnosis of depression was recorded. The use of diagnoses that primary care physicians coded sets a threshold that is not equivalent to recognition that might be assessed by direct inquiry of the physicians. Also, since the NAMCS only allows for the recording of 3 diagnoses, the physician conceivably recognized depression but did not record it because a higher priority was assigned to 3 other diagnoses. This quite conceivably is occurring with regard to visits by elderly patients who frequently experience multiple conditions. However, over 80% of visits by all subjects only had 1 or 2 diagnoses recorded during the visit, suggesting that in most cases, a depression diagnosis was not “crowded out.” Additionally, a sensitivity analysis conducted only on visits where 2 or fewer diagnoses were recorded during the visit found the same factors associated with a recorded depression diagnosis. The NAMCS data also only allows for the recording of 3 patient reasons for the visit. If a patient had more than 3 reasons for the visit, only the top 3, as identified by the physician, were recorded in the survey. This could lead to important patient symptoms being excluded from the survey. Thus, the analysis could not perfectly control for all the patients’ reasons for the visit, and this limitation should be kept in mind when interpreting these findings. Another limitation of the data is that no assessment of history of depression that might be an important clue for primary care physicians is recorded in the NAMCS survey.

Conclusions

There are many factors associated with physician recording of a depression diagnosis beyond the patient’s reported symptoms. Therefore, if rates of diagnosis of depression in office-based practice are to more closely approximate the true prevalence of the disorder, interventions are needed that go beyond simply helping physicians to better recognize the symptoms of depression. A recent review found that approximately one fourth of interventions designed to increase recognition and management of depression had no effect on diagnosis and treatment rates.⁶ Perhaps their effectiveness could be improved by designing more focused interventions that target African American and elderly patients who presently are assigned low rates of depressive diagnoses in primary care. This is a particularly high priority, since both African American and elderly patients are more likely to seek treatment in the primary care sector rather than the mental health specialty sector. Solberg and colleagues²⁵ found that primary care physicians viewed systematic screening unfavorably, but were supportive of alternative approaches, such as external feedback about the care that they provide. Thus, feedback about differences in age-and race-specific rates could possibly provide the impetus needed for primary care physicians to alter their assessment procedures and clinical formulations in these under-recognized groups of patients. Finally, intervention efforts may want to focus on the unique manner in which internists formulate psychiatric diagnoses, since recognition rates for depression are unduly low in this specialty group.

Acknowledgments

This research was supported in part by National Institute of Mental Health grants P30 MH3095, P30 MH52247, R25 MH60473, K01 MH01613, and R01 MH59318.

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