Study of prevalence of depression and impact of depression in patients following acute myocardial infarction

Background: Depression has been found to be associated with cardiovascular diseases in various studies done in different parts of the world. Whether depression really develops after an attack of acute myocardial infarction (AMI) in hospitalised patients was not evaluated in this region of our country prior to the current work. Aim: To evaluate the prevalence of depression and impact of depression in AMI patients during the period of hospitalisation. Materials and Methods: Patients were recruited for the study after fulfi lling the selection criteria and who had documented AMI within four to fi ve days of hospitalisation. Informed consent of the patient and ethical committee clearance was obtained. To collect data semi-structured interview schedule was used. Assamese versions of 21 self-report items Beck Depression Inventory (BDI) and observer-rated 17 items Hamilton Rating Scale for Depression (HAM-D) were administered to 50 AMI patients. Data were analysed with chi-square test, Pearson coeffi cient of correlation, and student t test wherever applicable. p-value<0.05 was considered test of signifi cance in this study. Result: Fifty cases of AMI were evaluated from August 2007 to July 2008. Thirty six per cent of AMI patients and 34% of AMI patients were found to have depression as per BDI and HAM-D scales respectively. Depression has an impact on duration of hospital stay signifi cantly (p<0.019) but not on gender difference (p=0.089). Correlation of mean scores of both HAM-D and BDI scales was done by Pearson coeffi cient of correlation and was found to be signifi cant at .01 level. Conclusion: Depression was found to be high in AMI patients during the period of hospitalisation in both the depression rating scales and it has an impact on prognosis of the patients.


Introduction
Acute myocardial infarction (AMI) is a common presentation of ischaemic heart disease (IHD).Th e classical symptoms of AMI include sudden onset of chest pain, shortness of breath, nausea, vomiting, palpitation, and anxiety.It generally occurs when there is thrombotic occlusion of atherosclerotic coronary artery.Th e World Health Organization (WHO) estimated that in 2002, 12.6% deaths worldwide were from IHD.In India, cardiovascular disease (CVD) is the leading cause of death.[1] One study from rural area of Rajasthan, India had reported that CHD contributes to eight per cent of patients attending a general physician's clinic.[2] In India, typically acute coronary events occur at least ten years earlier than in Caucasian and Latin American countries.[3] AMI was previously defi ned by clinical fi ndings, electroencephalography (ECG), and laboratory investigations.But current acceptable defi nition is as per redefi ned criteria by Joint European Society of Cardiology and American College of Cardiology Committee.[4] All medically ill patients do experience depression during their illness period but it is not always detected or evaluated.In current scenario, depression is a widely prevalent illness.Th e World Health Organization (WHO) projects that by the year 2020, depression will remain a leading cause of disability, second only to cardiovascular disease, accounting for 11% of world's total disease burden.[5] It is seen that AMI patients with depression have an approximate two to four fold risk of mortality compared to non-depressed patients.[6,7] Studies looking at patients aft er AMI have reported prevalence rates of depression ranging from 16 to 23%, [8,9] It has been found that patients suff ering from depression are three times as likely to be noncompliant with medical treatment regimes compared to non-depressed patients.[10] Similar fi ndings relating to drug adherence are reported from this part of the globe as well.[11] Depression has been found to be related with reduced quality of life to a degree or greater than that of other chronic health problems.[12][13][14] Th us evaluation of depression may be helpful in providing proper diagnosis and treatment in patients with AMI.Several studies on depression in AMI have been done in the West and fi ndings have been heterogenous in terms of symptomatology, aetiology, and responsivity to particular treatment.Compared to the West, very few studies have been done in India and the present study will be the fi rst of its kind in this institution.Th is study thus intends to fi nd whether depression really exists aft er AMI so that we can take holistic approach to their problems and relieve them of their distress.

Aim and objective
1. To evaluate the prevalence of depression in patients hospitalised following AMI. 2. To fi nd out the impact of depression on duration of hospital stay in patients with AMI. 3. To see the correlation between the depressive scores on both the depression rating scales.

Place of study
Th is study has been conducted on patients admitted in the Department of Cardiology of Gauhati Medical College and Hospital (GMCH).GMCH is a tertiary care institute situated in Guwahati and receives patients from Assam as well as entire North-East India.

Period of study
Th e period of study extended from August 2007 to July 2008.

Study design
Th is is a cross sectional study.
Th e study sample comprised of fi ft y consecutively selected subjects admitted in the Department of Cardiology of GMCH and diagnosed as having AMI and meeting the selection criteria.Th e diagnosis of AMI was made using the redefi ned criteria for AMI by the consultant of cardiology department.

Inclusion criteria
1.Both male and female patients.

Tools used for assessment
1.A semi-structured interview schedule to collect the socio-demographic data.2. Hamilton Rating Scale for Depression (HAM-D).

Translated and validated version of Beck Depression
Inventory (BDI).

Method of collecting information
Ethical clearance for the study has been obtained from the institutional ethical committee.Aft er selecting subjects as per selection criteria, an informed consent for participation in the study was taken from all patients.Th e patient diagnosed with AMI as per selection criteria were then subjected to a detailed interview and tools were administered within four to fi ve days aft er hospitalisation.To assess the duration of hospital stay we collect information regarding date of discharge from indoor register book of the cardiology department.Th e register book has the record of date of admission and date and time of discharge of the patients.For all cases, privacy of interview and confi dentiality were strictly maintained.

Results
From Table 1 it is evident that percentage of males in AMI patients was 84% and that of females was 16%.Again the mean age in males is 50.1 years; on the other hand, the mean age of female is 56.4 years.
Table 2 shows number and percentage of patients having depression according to BDI.Amongst the male and female patients total 36% was depressed and the mean score on BDI was 15.11.Table 2 also represents the sex distribution of depressed and non-depressed AMI patients.When sex diff erence was compared between depressed and non-depressed AMI patients no statistically signifi cant diff erence was found (chi-square 2.902, p=0.089).Th e table shows number and percentage of patients and severity of depression.Th irty six per cent of the patients had depression clinically.Twenty six per cent of patients were having mild depression and ten per cent having moderate depression according to BDI.No severely depressed patient was found among them.Th e table also shows number and percentage of patients having depression according to HAM-D scale.Amongst the male and female patients 34% were found to be depressed and the mean score on HAM-D scale was 12.90.Th e table shows that 36% of patients had clinically signifi cant depression according to BDI and 34% of patients had clinically signifi cant depression according to HAM-D scale.
Th e coeffi cient of correlation between BDI and HAM-D is 0.890.Th e correlation is signifi cant at the 0.01 level, hence the relationship is signifi cant.Th e table also shows that the mean duration of hospital stay among the non-depressed patients was 8.375 days and the mean duration of hospital stay among depressed patient was 9.333 days.Th e diff erence of mean duration of hospital stay among the depressed and non-depressed is 2.43, which is a signifi cant value, indicating higher duration of hospital stay by the depressed patients.

Discussion
Our study found that prevalence of depression is 36% in the patients with AMI within fi ve days of hospitalisation.Th e  [18] found score on BDI more than ten in 35% cases of AMI within two to three days of hospitalisation.Lesperance et al. [19] reported 32% of post AMI patients had score on BDI more than ten within two to fi ve days of hospitalisation.Similarly, Lane et al. [20] reported 30% of post AMI patients had score on BDI more than ten within 15 days of hospitalisation.
Our fi nding of 36% cases of depression in patients with AMI is slightly higher than that found by other studies.Bush et al. [6] reported 20% of AMI cases scored above ten on BDI during the period of hospitalisation.Davis and Jansen [21] found that only ten per cent of AMI cases had BDI score above 13 during hospitalisation.Luutonen et al. [22] found depression in 21% of the cases.On the other hand, prevalence of depression found in this study is lower than that reported by Steeds et al. [23] Th e prevalence of depression in their study was 47%.
Prevalence of depression in AMI during the period of hospitalisation has been reported by many studies.Schleifer et al. [24] found that 45% of post AMI patients met diagnostic criteria for major or minor depression during eight to ten days aft er hospitalisation.Carney et al. [25] reported prevalence of depression in 23% of AMI patients fi ve to seven days aft er hospitalisation.Bennett and Mayfi eld [26] reported prevalence of depression to be 13% within one week of AMI.Several studies have found prevalence of depression during the period of hospitalisation following AMI.[27][28][29][30] When severity of depression was assessed across the AMI patients, mild depression was found at the rate of 26%, followed by moderate depression in ten per cent.In our study, none of the AMI patients were found to have severe depression.Mild to moderate symptoms of depression have been reported by Western studies on BDI.[6,[18][19][20] We have also administered HAM-D and prevalence of depression is found to be 34% in AMI.Mean score on 17 items HAM-D scale is 12.90.Th e prevalence of depression is similar with the fi ndings of Mahapatra et al. [31] but the mean score in their study is 15.0±5.33,which is higher than our fi ndings.On the other hand prevalence of depression was found to be lower in Western studies according to 17 items HAM-D scale.Barefoot et al. [32] found that prevalence of depression was 28% in AMI patients.But Taylor et al. [33] reported prevalence of depression in only 13% cases.
Correlation between BDI and HAM-D mean scores have been evaluated and a signifi cant correlation was found at .01 level.High correlation of BDI and HAM-D scores was reported by Back et al. [34] In their study mean correlation of BDI with clinical ratings and HAM-D were 0.72 and 0.73 respectively in psychiatric subjects.With non-psychiatric subjects the mean correlations of BDI and HAM-D were 0.60 and 0.74 respectively.
We also evaluated the impact of depression on gender diff erence and duration of hospital stay.We did not fi nd impact of depression on gender diff erence in AMI patients.It was not statistically signifi cant (p=0.089) in contrast to the study done by Parashar et al. [35] where depressive symptoms were more prevalent in women compared with men (29% versus 18.8%, p<0.001).It may be due to less female data in our study as literate in Assamese was an inclusion criteria.In our sample 84% AMI cases were male and 16% were females although male preponderance in AMI cases has been reported by Mahapatra et al. [31] On evaluation of duration of hospital stay in AMI cases we found that the mean duration of hospital stay in depressed AMI patients was 9.333 and in case of non-depressed group it was 8.375.On statistical analysis this diff erence was found signifi cant (p=0.019)indicating higher duration of hospital stay by the depressed AMI patients than the nondepressed group.In our study, mean duration of hospital stay in non-depressed AMI patients was similar with the report of Varnava et al. [36] In their study median duration of hospital stay was six to eight days.But the result of Skoulas et al. [37] and McNeer et al. [38] were higher than our fi ndings of non-depressed AMI patients.McNeer et al. [38] had reported mean duration of hospital stay of AMI patients to be 11±2 days and Skoulas et al. [37] reported 9.7 days, on the other hand Lauzon et al. [18] reported median length of hospital stay was 12 days in case of BDI score above ten, and in case of BDI score less than ten had duration of hospital stay of 11 days.Th is is higher than our fi ndings.Mayou et al. [39] reported mean duration of hospital stay in emotionally distressed and non-distressed AMI patients to be 10.14 and 8.31 respectively, which is slightly higher than our fi ndings.But duration of hospital stay in non-depressed group is similar with our fi ndings.

Limitations
Our study has certain limitations.Firstly, the sample taken was small.A larger sample would have been more representative.Secondly, we have not assessed the severity of AMI and whether the higher depressive scores are related to severity of AMI has not been evaluated.Th irdly, being a cross sectional study the patients were assessed only once within four to fi ve days following AMI, therefore follow up study will determine the impact of depressive symptoms on future prognosis of AMI.A recent published work from this part followed up such patients.[40]

Conclusions
Despite the limitations, on the basis of the fi ndings in our study we can make the following conclusions: 1. AMI patients have signifi cantly higher scores on both the depression rating scales.2. Prevalence of depression was found to be high during the period of hospitalisation.3. Depression has a signifi cant negative impact on prognosis of AMI patients during hospitalisation.
From the fi ndings of this study we can thus recommend that the clinical and nursing staff of cardiology department should be aware of depressive symptoms appearing aft er AMI or admitted with AMI, as there have been observations that untreated depressive patients have high mortality rate than treated post-AMI depressive patients.Routine psychological assessment of AMI patients in hospital should be a part of the management of these groups of patients.Many of these patients suff ered from mild to moderate depression and can be treated by psychotherapeutic intervention necessitating antidepressant medication in a small group.Management of depression in these groups of patients improves treatment compliance, life style modifi cation, and thereby leading to a better quality of life.

Table 1 :
Distribution of study population based on socio-demographic data mean score on BDI in AMI patients was 15.11.Our fi nding is almost similar with other Western studies.Lauzon et al.

Table 2 :
Distribution of study population based on clinical data