Long Term Effect of Depression Care Management on Mortality
Long Term Effect of Depression Care Management on Mortality
Figure 1 shows the consolidated standards of reporting trials (CONSORT) flow diagram. Table 1 compares baseline characteristics between patients who met criteria for major depression or minor depression and patients without depression, according to the intervention status of practices. Compared with patients without depression, those in both arms with major depression were more likely to smoke, to report heart disease or gastrointestinal disease at baseline, to have higher depression scores, and to report suicidal ideation. Patients with minor depression were comparable to people without depression, with the exception of higher depression scores and, in the intervention condition, being more likely to report smoking, gastrointestinal disease, and suicidal ideation. At baseline, the 37 smokers with major depression in intervention practices reported smoking an average of 16.9 (SD 12.6; median 18, interquartile range 10-20) cigarettes a day. In usual care, 41 smokers with major depression reported smoking an average of 16.5 (SD 14.4; median 14, interquartile range 7-20) cigarettes a day.
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Figure 1.
Flow chart for mortality follow-up of PROSPECT patients. CES-D=Centers for Epidemiologic Studies depression scale.
The median length of follow-up in ascertainment of vital status was 98 (range 0.8-116.4) months, during which 405 people died—215 depressed patients and 190 non-depressed patients. Figure 2 shows Kaplan-Meier curves for baseline depression status according to intervention condition. Table 2 reports final Cox proportional hazards models and number of deaths in terms of depression stratified by intervention condition versus usual care. We observed no significant departure from the proportional hazards assumption (P=0.10; χ=4.57, df=2). The hazard ratio for patients with major depression compared with patients without depression in usual care was 1.90 (95% confidence interval 1.57 to 2.31). In contrast, for patients with major depression compared with non-depressed patients in the intervention condition, the hazard ratio was 1.09 (0.83 to 1.44). We found no similar relation for clinically significant minor depression. Thus, patients with major depression in usual care practices were twice as likely to die as patients without depression, whereas the risk for patients with major depression in intervention practices was similar to that for people without depression.
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Figure 2.
Survival probability among people with no depression or major depression in practices randomized to usual care (top panel) or to intervention (bottom panel). Data from PROSPECT (1999-2008).
When we compared patients with major depression in the intervention condition with patients with major depression in usual care, the hazard ratio in the adjusted model was 0.76 (0.57 to 1.00), indicating that patients with major depression were 24% less likely to have died over follow-up if they had received the PROSPECT intervention. The corresponding hazard ratio of 1.18 (0.77 to 1.81) for people with minor depression was not statistically significant.
Figure 3 illustrates the adjusted hazard ratios (with 95% confidence intervals) for specific causes of death according to practice randomization assignment for patients with major depression. Among people with major depression, compared with people without depression, the risk of death from cancer was significantly higher in usual care. We found no statistically significant hazard ratios for minor depression (data not shown). Cancers causing death among patients with major depression in usual care (n=26) were respiratory in 10 patients, digestive in five, hematopoietic in four, female genital in two, and unspecified in two, with one each of breast, male genital, and urinary tract origin. In intervention practices, cancers causing deaths among patients with major depression (n=15) were respiratory in nine patients and digestive in two, with one each of breast, male genital, hematopoietic, and unspecified origin. Among 37 people with major depression in intervention practices who reported smoking at baseline, seven died of cancer (six were respiratory cancer); among 41 patients with major depression in usual care who reported smoking at baseline, six died of cancer (five were respiratory cancer). Among 32 people in intervention practices who did not meet criteria for major or minor depression and who reported smoking at baseline, seven died of cancer (three were respiratory); among 40 smokers in usual care without depression, nine died of cancer (four were respiratory).
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Figure 3.
Adjusted hazard ratios (95% CI) for specific causes of death comparing major depression with no depression within intervention or usual care practices. Data from PROSPECT (1999-2008). Hazard ratios are from Cox proportional hazards models. Adjusted models included terms for baseline age, sex, education, marital status, smoking, cardiovascular disease, stroke, diabetes, cancer, cognition, and suicidal ideation.
Results
Characteristics of Sample
Figure 1 shows the consolidated standards of reporting trials (CONSORT) flow diagram. Table 1 compares baseline characteristics between patients who met criteria for major depression or minor depression and patients without depression, according to the intervention status of practices. Compared with patients without depression, those in both arms with major depression were more likely to smoke, to report heart disease or gastrointestinal disease at baseline, to have higher depression scores, and to report suicidal ideation. Patients with minor depression were comparable to people without depression, with the exception of higher depression scores and, in the intervention condition, being more likely to report smoking, gastrointestinal disease, and suicidal ideation. At baseline, the 37 smokers with major depression in intervention practices reported smoking an average of 16.9 (SD 12.6; median 18, interquartile range 10-20) cigarettes a day. In usual care, 41 smokers with major depression reported smoking an average of 16.5 (SD 14.4; median 14, interquartile range 7-20) cigarettes a day.
(Enlarge Image)
Figure 1.
Flow chart for mortality follow-up of PROSPECT patients. CES-D=Centers for Epidemiologic Studies depression scale.
Mortality Risk Attributable to Depression in Intervention versus Usual Care
The median length of follow-up in ascertainment of vital status was 98 (range 0.8-116.4) months, during which 405 people died—215 depressed patients and 190 non-depressed patients. Figure 2 shows Kaplan-Meier curves for baseline depression status according to intervention condition. Table 2 reports final Cox proportional hazards models and number of deaths in terms of depression stratified by intervention condition versus usual care. We observed no significant departure from the proportional hazards assumption (P=0.10; χ=4.57, df=2). The hazard ratio for patients with major depression compared with patients without depression in usual care was 1.90 (95% confidence interval 1.57 to 2.31). In contrast, for patients with major depression compared with non-depressed patients in the intervention condition, the hazard ratio was 1.09 (0.83 to 1.44). We found no similar relation for clinically significant minor depression. Thus, patients with major depression in usual care practices were twice as likely to die as patients without depression, whereas the risk for patients with major depression in intervention practices was similar to that for people without depression.
(Enlarge Image)
Figure 2.
Survival probability among people with no depression or major depression in practices randomized to usual care (top panel) or to intervention (bottom panel). Data from PROSPECT (1999-2008).
Mortality Risk of Major Depression in Intervention versus Usual Care
When we compared patients with major depression in the intervention condition with patients with major depression in usual care, the hazard ratio in the adjusted model was 0.76 (0.57 to 1.00), indicating that patients with major depression were 24% less likely to have died over follow-up if they had received the PROSPECT intervention. The corresponding hazard ratio of 1.18 (0.77 to 1.81) for people with minor depression was not statistically significant.
Mortality According to Cause of Death
Figure 3 illustrates the adjusted hazard ratios (with 95% confidence intervals) for specific causes of death according to practice randomization assignment for patients with major depression. Among people with major depression, compared with people without depression, the risk of death from cancer was significantly higher in usual care. We found no statistically significant hazard ratios for minor depression (data not shown). Cancers causing death among patients with major depression in usual care (n=26) were respiratory in 10 patients, digestive in five, hematopoietic in four, female genital in two, and unspecified in two, with one each of breast, male genital, and urinary tract origin. In intervention practices, cancers causing deaths among patients with major depression (n=15) were respiratory in nine patients and digestive in two, with one each of breast, male genital, hematopoietic, and unspecified origin. Among 37 people with major depression in intervention practices who reported smoking at baseline, seven died of cancer (six were respiratory cancer); among 41 patients with major depression in usual care who reported smoking at baseline, six died of cancer (five were respiratory cancer). Among 32 people in intervention practices who did not meet criteria for major or minor depression and who reported smoking at baseline, seven died of cancer (three were respiratory); among 40 smokers in usual care without depression, nine died of cancer (four were respiratory).
(Enlarge Image)
Figure 3.
Adjusted hazard ratios (95% CI) for specific causes of death comparing major depression with no depression within intervention or usual care practices. Data from PROSPECT (1999-2008). Hazard ratios are from Cox proportional hazards models. Adjusted models included terms for baseline age, sex, education, marital status, smoking, cardiovascular disease, stroke, diabetes, cancer, cognition, and suicidal ideation.
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