Utility
Sensitivity to Change
An important issue bearing on the utility of a mental health assessment instrument is its ability to monitor response to treatment. To evaluate the utility of the QPD Panel depression and anxiety scales for treatment monitoring, we studied a sample of depressed patients longitudinally.27 The research participants were 113 HMO patients identified by their PCPs during routine primary care office visits as suffering from depressive disorders. The sample was 77.9% women, with a mean age of 41 years (SD=12.69). To establish baseline depression scores, participants were administered the QPD Panel and the Zung Self-Rating Depression Scale at the time of their initial medical office visit (pretreatment). They were then treated for depression with antidepressant medication, brief psychotherapy, or both. The QPD Panel and the Zung depression scale were readministered at 4 and 12 weeks after initiation of treatment.
[Figure 2] shows changes in the QPD Panel depression and anxiety scores from pretreatment through 12 weeks after initiation of treatment. The mean QPD Panel Depression score was 14.8 (SD=5.64) at baseline, 11.2 (SD=6.7) at 4 weeks posttreatment, and 7.7 (SD=6.6) at 12 weeks posttreatment, representing a change from baseline of approximately 50%, or somewhat more than 1 standard deviation, in the anticipated direction. Changes in the QPD Panel scores were paralleled by changes in Zung depression scores, which also declined by slightly more than 1 standard deviation during the same interval. Additionally, QPD and Zung depression scores were highly correlated at every assessment point (rs from .62 at baseline to .84 at 12 weeks post-treatment). The findings indicate that the QPD Panel is useful for treatment monitoring as well as initial screening.
Physician Acceptance
[Table 4] presents findings from a physician satisfaction survey conducted to formally evaluate the utility of the QPD Panel in a busy primary care setting. Data were provided by a sample of 26 primary care providers (physicians and nurse practitioners) practicing at one of 2 outpatient medical facilities in a large group model HMO in the Denver area. Physicians in these clinics see approximately 20 to 24 patients per day, with appointments scheduled at 15- to 20-minute intervals. Physicians who participated in the study used the QPD Panel on a routine basis for 1 month or longer. No incentives were given to the medical facilities or the physicians to use the QPD Panel or participate in the satisfaction study. Physicians rated each statement listed in Table 4 using a 5-point rating scale (1=strongly disagree; 5=strongly agree). Means for the physician satisfaction items were uniformly high and near the scale maximum of 5.0. As another way of presenting the data, the last column of Table 4 lists the percentage of clinicians who agreed or strongly agreed with each survey statement. The data demonstrate the high physician acceptance achieved by the QPD Panel.
Patient Satisfaction
PCPs sometimes express the concern that patients will object to mental health screening or regard the screening questions as inappropriate or intrusive. To evaluate this possibility, we asked a sample of 77 HMO patients who had completed the QPD panel to respond to 4 survey questions using an agree or disagree response format. Of these, 97% agreed with the statement “the questionnaire was easy to use”; 99% agreed “the questions were clear and easy to understand”; 96% agreed “the questionnaire asks about things that are important for my doctor to know”; and 96% disagreed that “The questions were too personal and made me feel uncomfortable.”
Discussion
Although many health care experts agree that there is a need for improved mental health screening in primary care, mental health case-finding tools are not widely used in primary care settings. Previous studies have generally focused on the validity of case-finding instruments, but factors other than validity pose obstacles to implementation. Many physicians are also concerned about the time required to administer and score the instruments, their potential for disrupting office routines, the paperwork they create, whether they provide specific psychiatric diagnoses, and whether they can detect mental disorders other than depression.
Specificity of case-finding instruments is also a concern. A review of depression case-finding instruments reported an average specificity of 72%;12 another recent review advocated a 2-question screening test but reported a specificity of only 57%.28 It is important to recognize that a screening or case-finding instrument with a specificity of 72% will incorrectly identify as depressed 28 out of every 100 patients who are not depressed, and a test with a specificity of 57% will incorrectly identify 43. These false-positives are costly in terms of physician time and make case-finding instruments less attractive to busy practitioners.