Changes in depressive symptoms and functioning are summarized in [Table 3]. As a group, patients improved significantly on the SCL-25 depression scale and in the SF-36 functional domains thought to be most affected by mental disorders: vitality, social functioning, role functioning-emotional, and mental health. There were no comparable changes in SF-36 domains related to physical functioning, despite significant limitations in these domains at enrollment. Aggregate changes appeared to be the result of moderate improvements in many patients rather than dramatic changes in a minority.
However, despite significant improvements, patients continued to demonstrate deficits in all SF-36 domains compared with United States norms at follow-up (P <.001 for all domains). The majority (60%) also continued to have clinically significant depressive symptoms on the SCL-25.
Predictors of Improvement
Exploratory analyses of factors associated with improvement indicated that patients with more symptomatic or functional impairment at baseline showed the most improvement at follow-up. Having chronic depressive symptoms (patient report of feeling depressed most days during the last 2 years) was associated with less improvement in depression scores. Sex, age, concurrent mental health treatment at the time of enrollment, treatment with medication during follow-up, and number of concurrent medical conditions did not predict improvement.
Discussion
Only a small percentage of primary care patients are identified as depressed in encounter or administrative data, and these patients have relatively severe, recurrent DSM depressive disorders and high levels of symptoms at the time of the notations. Thus, organizations using administrative data to target patients for QI efforts will likely select a population with clinically significant and currently symptomatic disorders.
Most patients identified in this manner will have received standard treatments in the past, including medication and psychotherapy, and will continue to receive antidepressant medication during follow-up, even without QI intervention. A substantial minority will also receive concurrent treatment by a MHP.
Although QI programs will find that most patients identified in encounter data improve during the next 5 to 12 months, these patients are likely to continue to experience significant depressive symptoms and functional limitations in SF-36 domains. Patients improve more in functional domains related to mental health than physical health, suggesting that some improvements could be due to treatment; however, some improvements may also be due to regression to the mean.
These findings have implications for organizations that are considering using administrative data to select patients for QI programs. Since patients identified in this manner are likely to be highly symptomatic, meet full criteria for DSM depressive disorders, and continue to experience symptoms over time-despite receiving antidepressants and having intermittent contact with MHPs-limited QI programs may not be sufficient. QI programs that simply assure the provision of antidepressants or encourage referral to mental health professionals, while undoubtedly helpful for some populations of patients, are unlikely to improve the outcomes of this target group. More intensive QI programs may be required, such as programs that monitor clinical status or offer intensive alternatives, such as a disease management or stepped care.
Limitations
Several limitations should be considered when interpreting our findings. First, our study was conducted in only 2 sites. Physicians in other settings may be more or less likely to note depressive diagnoses in administrative data. Many settings will not have MHPs available on a consultative basis; having this availability may affect the frequency of depression diagnosis or treatments prescribed. A PCP’s willingness to make an encounter diagnosis of depression is likely influenced by a number of factors, including the characteristics of the clinic population, clinic norms, team composition, and reimbursement policies of third-party payers.
Only 25% of the patients identified as depressed in administrative data were enrolled in our study, and the possibility of systematic selection must be carefully considered. Biases may have been introduced by many factors: variation in PCP willingness to have patients recruited into the study; which patients were approved for recruitment; who could be contacted by telephone; who agreed to participate; and the shorter recruitment route for patients seen by the psychiatrist. Most potential enrollees were lost simply because clinicians failed to respond to written requests for permission to contact their patients. Yet, more than 60% of patients were retained at each step in the enrollment process, and no systematic differences were found between enrolled and nonenrolled patients in sex, clinic site, or encounter diagnosis. Although there was considerable variation in the time to follow-up assessment, with mailed assessments being returned between 5 and 12 months, time frames of 6 to 12 months are commonly used in QI studies of depression outcomes.