“Patient knows best”—detection of common mental disorders in Santiago, Chile: cross sectional study

Depression and anxiety are common in primary care but about half of patients with these disorders are not identified by primary care physicians.¹,² Mental disorder is more likely to be diagnosed in patients who present with or attribute physical symptoms to psychological causes.^2–4 We investigated how patients' ways of understanding their health problems influenced the detection of common mental disorder by primary care physicians in Santiago, Chile.

Methods and results

We studied 815 consecutive patients seen by 11 primary care physicians from five randomly selected clinics in northern Santiago, Chile. Patients with a chronic illness or patients aged over 50 were excluded because these patients are better known by doctors. Most doctors in Chile and in this study have less than four years' experience in primary care.

Before the patient saw the doctor, a lay interviewer asked the patient's reason for consultation and whether it was because of a physical or psychological problem. The interviewer inquired about other potential confounders: physical illness, disability, common somatic symptoms, and whether patients tended to interpret common somatic symptoms by using psychological, physical, or normalising explanations.

A psychiatrist administered the clinical interview schedule—revised, and patients scoring 12 or more were classified as having a common mental disorder.⁵ After the patient had seen the primary care physician, the doctor rated blindly whether the patient had a mental disorder using a five-point scale. Patients with a rating of “mild or greater” severity were considered to have a mental disorder.

The prevalence of mental disorders was 49% (396 of 802; 95% confidence interval 46% to 53%) according to the clinical interview schedule—revised and 35% (276 of 796; 31% to 38%) according to the doctors' ratings. Agreement of doctors' ratings was 48% (186 of 385; 43% to 53%) with the psychiatric assessment (κ=0.27), so 52% (199 of 385; 47% to 57%) of the cases identified by the clinical interview schedule went undetected. As a whole, 34% (269 of 795; 30% to 37%) of the patients chose a psychological explanation for their reason for consultation but only 69% (185 of 269; 63% to 74%) of them were psychiatric cases according to the psychiatric interviewer.

When analysis was restricted to psychiatric cases, almost half (48%) (186 of 389; 43% to 53%) of these patients attributed their reason for consultation to psychological causes. Among psychiatric cases, doctors identified correctly 34% (70 of 204; 28% to 41%) of those who attributed their reason for consultation to physical causes and 63% (116 of 185; 55% to 70%) of those who attributed their presenting problems to a psychological cause. After adjustment for confounders three variables showed significant independent associations with detection (table): a spontaneous psychological reason for consultation, a psychological causal attribution for the presenting problems, and an increased severity of the mental disorder.

Comment

Patients in primary care with mental disorders usually consult with doctors for physical problems and this can make it difficult for primary care physicians to identify mental disorder. However, our study has found that a substantial proportion of patients presenting with physical problems readily acknowledge that there is a psychological component to their physical problems. Doctors were more likely to identify patients with mental disorder who attributed their symptoms to a psychological cause than to a physical cause. Asking the patient directly about possible causes of their symptoms might be a simple way of improving the identification of mental disorder in primary care.

Learning how best to clarify patients' presenting complaints should be an important objective of communication skills programmes for clinicians. This could help improve detection rates of mental disorders, compliance, and patients' satisfaction with management. Patients' views are even more important when evidence based knowledge is difficult to come by and clinical uncertainty more common.

Table.

The association between patients' causal attribution (physical or psychological) of the reason for consultation and the detection of common mental disorders by primary care doctors. Only cases diagnosed according to psychiatric interview are included

	No*	Crude odds ratio (95% CI)	Adjusted odds ratio† (95% CI)
Reason for consultation‡:
Physical	168	1	1
Ambiguous	136	2.20 (1.31 to 3.69)	1.33 (0.72 to 2.48)
Psychological	26	22.9 (5.7 to 92.2)	6.24 (1.27 to 30.6)
Patients' causal attribution:
Physical	206	1	1
Psychological	181	3.22 (2.12 to 4.87)	2.31 (1.43 to 3.74)
Physical illness:
Absent	274	1	1
Present	108	0.73 (0.46 to 1.15)	0.54 (0.28 to 1.05)
Disability:
Absent	245	1	1
Present	150	1.05 (0.77 to 1.42)	0.91 (0.55 to 1.46)
Common somatic symptoms:
Below median	118	1	1
Above median	262	2.45 (1.50 to 3.98)	1.30 (0.74 to 2.28)
Symptom interpretation questionnaire:
Psychologising:
Below median	149	1	1
Above median	233	1.57 (1.04 to 2.37)	0.81 (0.36 to 1.79)
Somatising:
Below median	182	1	1
Above median	200	0.95 (0.63 to 1.42)	1.10 (0.67 to 1.80)
Normalising:
Below median	247	1	1
Above median	135	0.53 (0.34 to 0.81)	0.75 (0.37 to 1.52)
Clinical interview schedule—revised score:
12-20 points	186	1	1
>20 points	210	2.04 (1.22 to 3.39)	2.00 (1.15 to 3.50)

^*Number of subjects included in the calculation of crude odds ratios. 

^†Logistic regression involved 291 subjects only, because cases with missing data are automatically omitted from the procedure. Using Huber White Robust Estimator for clustering of doctors and adjusted for all study variables. 

^‡Fifteen cases are missing and 55 cases are not included because reasons for consultation were unclear or patients were consulting primarily for administrative reasons (for example, physical check ups, to obtain a sickness note, and so on).