Another study (Philibert et al., 1995) found no difference in mortality rates of patients aged 65 or older in the first nine months but did find a significant overall difference over a ten year period (ECT 37%, non-ECT 45%) The causes of death were not cited. About half the non-ECT group had in fact received ECT prior to the study period. The authors acknowledged that those who had not received ECT “were more likely to have had prior myocardial infarction, to have coexisting chronic obstructive pulmonary disease and to have been initially hospitalized on the medical-psychiatric unit, an area for patients with both medical and psychiatric diagnoses, than those receiving ECT as their first treatment”.