It has consistently been shown that a link exists between older adults who have depression and mortality (Cuijpers & Smit, 2002, Schulz et al., 2002). RCTs have demonstrated that treating depression during later life in primary care settings can result in the remission of depression and its associated symptoms as well as improve quality of life for individuals.

Recently, an RCT was conducted by Gallo and colleagues (2013) which aimed to investigate whether an intervention to improve treatment for older adults with depression in primary care modified the increased risk of death which is associated with depression.

The study shows that older adults with major depression in practices provided with extra resources to intensively manage their depression had a lower mortality risk compared to those in usual care and similar to older adults who don’t have depression.

Methods

• Study type: The study was a randomised control trial.

• Location: PROSPECT (Prevention of Suicide in Primary Care Elderly) was conducted in 20 primary care practices located in America from May 1999 to August 2001.

• Participants: The 1226 participants were aged 60-75 years and had upcoming appointments at primary care settings.

• Inclusion Criteria: Participants had to be over 60 years in age, have a mini-mental state examination score greater than 17 and had to be able to speak English.

• Measures: Patients were screened for depression using the Centers for Epidemiologic Studies Depression Scale (CES-D). Patients with a score over 20 and 5% of the sample with lower scores were invited to participate.

• Length of treatment: The study took place for two years.

• Conditions: Practices were randomized to either the intervention or usual care. In the intervention condition, a depression care manager worked with primary care physicians in intervention practices to provide algorithim based care for depression and offered psychotherapy, increased antidepressant dose if required, and monitored symptoms, adverse effects of drugs and adherence to treatment. Primary care physicians received education of patient’s families. Participants in the usual care condition received educational sessions for primary care physicians and notification of patients’ depression status.

• Outcome measures: The main outcome measure for this study was mortality risk based on a median follow-up of 98 months to the year 2008.

Results

Overall, 213 patients died out of 616 in the intervention group over 98 months of follow-up.  In the usual care group, 192 died out of 622 patients.  Looking at the outcomes in more detail, the authors reported:

• Patients with major depression in intervention practices compared to usual care were 24% less likely to have died (hazard ratio 0.76, 0.57 to 1.00, p=0.05).
• Patients with major depression in usual care were more likely to die than those without depression (hazard ratio 1.90, 95% confidence interval 1.57 to 2.31).
• Patients with major depression in intervention practice were at no greater risk than people without depression (hazard ratio 1.09, 0.83 to 1.44).
• There was no significant effect of mortality on minor depression.

We disagree with these conclusions based on the evidence presented here.  The above results came from an “adjusted model”.  It is not clear exactly what adjustments were made.  However, when we looked at the absolute mortality numbers, we found that conducting the adjustment had shifted the conclusions in favour of additional treatments:

1. In the intervention group, there were 79 deaths amongst the 214 participants with major depression, an event rate or risk of 0.37, odds of 0.59
2. In the control group, 68 people died out of the 182 people with major depression, event rate or risk = 0.37, odds = 0.57
3. Thus the relative risk was 1.0 and the odds ratio was 1.04.

We don’t need to work out the confidence intervals to see that these values suggest “no difference” between the groups, in direct contradiction of the claims made by the adjusted model.  In the woodland, this sort of thing makes our elf-noses twitch.

Conclusions

The authors concluded:

Older adults with major depression in practices provided with additional resources to intensively manage depression had a mortality risk lower than that observed in usual care and similar to older adults with depression.

We don’t agree;  we don’t think that this trial provides sound evidence to support that conclusion, neither from the data reported, nor after consideration of the apparent methodological limitations described below.

Limitations and Summary

This study is the first of its kind from an RCT perspective which clearly shows that treating major depression in older adults using interventions in primary care settings can extend life.

It is not clear exactly who the study population was in this trial.  The participants were volunteers drawn from consecutive eligible patients attending the primary care practice.  The study does not say why they were attending the practice.  However, one might assume that they were “more ill” than the general population to begin with.

They did not provide an adequate rationale for including 5% of the eligible population whose CES-D score was 20 or less.

Since randomisation was carried out at the practice level, it is likely that selection bias occured because researchers could know which treatment group a patient would be assigned at the point at which they were invited to take part.

It seems almost certain that the two groups – intervention and usual care – were different at the start of the trial, and treated differently throughout. Therefore we cannot say that this trial provides reliable information about the research question.

The authors claimed that they used several strategies to control for factors that could have affected the findings. They matched practices on: urban location, academic affiliation, size and population type before randomization. Secondly, they adjusted estimates of risks and associated confidence bounds for clustering by practice and for patient level characteristics associated with mortality. Thirdly, they compared the mortality of patients with depression with non-depressed patients from the same sets of practices to mitigate the influence of unmeasured characteristics of practices.

However, misclassification for depression could have occurred and influenced the results. Depression and other mental health problems can be underestimated in older people as they can minimize their symptoms i.e. reports of sadness or anhedonia and because depressive symptoms are commonly attributed to physical health causes. The authors claim that trained research associates used PROSPECT which includes sensitive instruments (a clinical interview for axis 1 DSM-IV disorders and Hamilton Depression rating scale) to rate the severity of depression. Authors also discuss the strategies they used to control for vital status.

The implications of this study are that providing resources to primary care practices to integrate depression care management into chronic care management can extend life for older adults with depression. However, the case is far from proven and more evidence is needed to clearly establish these benefits.

Links

Gallo, J.J., Morales, K.H., Bogner, H.R., Raue, P.J., Zee, J., Bruce, M.L., Reynolds, C.F. (2013). Long term effect of depression care management on mortality in older adults: follow-up of cluster randomized clinical trial in primary care. British Medical Journal; 346:f2570.

Cuijpers, P. & Smit, F. (2002). Excess mortality in depression: a meta-analysis of community studies. Journal of Affective Disorders, 72, 227-236. [PubMed abstract]

Schulz, R., Drayer, B.L., R.A. & Rollan, B.L. (2002). Depression as a risk factor for non-suicide mortality in the elderly. Biological Psychiatry, 52, 205-225. [PubMed abstract]