PhD thesisThe M.D. Thesis study was an attempt to test the hypothesis that inpatients with medical illness who are depressed have worse outcomes, in terms of morbidity and mortality, than similar patients who are not depressed. This hypothesis was tested in four groups of patients who presented with life-threatening illness; myocardial infarction (n=100); sub-arachnoid haemorrhage ( n=41); pulmonary embolism ( n=40); and acute upper gastro-intestinal bleeding (n=30).
The patients entered into the trial underwent initial cognitive examination using the Mini-Mental State examination (MMS), to exclude patients with cognitive deficeits. This was followed by the Montgomery-Asberg Rating Scale for depression (MARS). These tests were repeated on alternate days until discharge, or 21 days post admission, whichever occurred sooner. The degree of pain experienced by the various groups of patients was measured using a simple Pain Rating Scale. The severity of illness for each individual patient was also computed, using currently available prognostic indicators. Four different cut-off points on the MARS were then used to determine the presence of depression. These cut-off points were 7, 14, 21 and 7 when the somatic components of the MARS were excluded (7-SCE).
The results showed that the depressed patients were not more seriously ill than the non-depressed group, regardless of the cut-off point used. There were also no significant diffences in age, sex, or pain experienced. Despite this equal prognosis for both the depressed and non-depressed groups, the former did significantly worse in all four conditionsn both in terms of morbidity and mortality. The most significant findings however, were when the patient populations were combined. Of the 211 patients, 55% were depressed when the cut-off point was 7, 41% when it was 14, 18% when it was 21 and 33% when it was 7-SCE. The 7-SCE group also consistently showed the most statistically significant differences between depressed and non-depressed patients in terms of outcome in all groups. In the 7-SCE group 46% had a poor outcome and 22% died, compared with 10% who did poorly and <2% who died in the non depressed group.
In studying the individual items of the MARS in patients who scored less than 14, then 80% of their score was due to somatic items which were likely to reflect the underlying illness. In the other cut-off points for depression this was approximately 50%. This risk of bias is inherent when using rating scales validated in the psychiatrically ill to detect depression in those with physical problems. The 7-SCE group is that in which the least likelihood of being affected by bias occurs.
The results also showed that the depressed patients experienced more pain, although this difference was not statistically significant. A further finding was the possibility that aneurysms of the right internal carotid artery were particularly associated with depression in those patients presenting with sub-arachnoid haemorrhage.
It was also clear from the change in the MARS over time that the phenomenon outlined above could more accurately be termed an adjustment reaction with depression rather than depressive illness
