Psychological distress and cardiovascular disease: results from the 2002 National Health Interview Survey
Amy K. Ferketich1,* and
Philip F. Binkley2
1Division of Epidemiology and Biostatistics, The Ohio State University School of Public Health, B-116 Starling-Loving Hall, 320 West 10th Avenue, Columbus, OH 43210, USA
2Division of Cardiovascular Medicine, Davis Heart and Lung Research Institute, The Ohio State University College of Medicine and Public Health, Columbus, OH, USA
Received 14 November 2004; revised 19 April 2005; accepted 22 April 2005; online publish-ahead-of-print 9 June 2005.
* Corresponding author. Tel: +1 614 293 4387; fax: +1 614 293 3937. E-mail address: aferketich{at}sph.osu.edu
See page 1820 for the editorial comment on this article (doi:10.1093/eurheart/ehi415)
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Abstract
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Aims The objective of this study was to examine the burden of psychological distress among individuals with different forms of heart disease in a large representative sample of adults.
Methods and results Data were obtained from the 2002 National Health Interview Survey, which is a large annual survey of the US non-institutionalized civilian population. Psychological distress was assessed with a standardized questionnaire (K6) and heart disease diagnoses were based on self-report. Among non-diseased individuals, the estimated prevalence of psychological distress was 2.8%, whereas the estimates were 10, 6.4, and 4.1% among those with congestive heart failure (CHF), myocardial infarction (MI), and coronary heart disease (CHD), respectively. Over 1 million individuals with one or more of these conditions are estimated to experience psychological distress. However, only 3135% of the participants with heart disease and psychological distress have visited a mental health professional. The logistic regression model results indicate that MI (OR 2.0, 95% CI 1.43.0) and CHF (OR 3.1, 95% CI 1.85.1) are significantly associated with psychological distress.
Conclusion These findings imply that psychological distress is a significant comorbidity of cardiovascular disease. Other investigations have demonstrated a link between psychological distress and morbidity and mortality. Taken together, these findings provide the impetus for future investigations that assess the role that a medical and mental health care professional intervention may have in altering these outcomes when targeted at this distress.
Key Words: Psychological distress Mental health Heart failure Myocardial infarction
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Introduction
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The literature on psychological distress and heart disease is expanding as investigators have moved from describing the association between the two conditions to examining the physiological mechanisms responsible for the comorbidity. However, many of the studies that have examined the burden of psychological distress in patients with heart disease have used either hospital samples or outpatient convenience samples. The main advantage in using a hospital sample of patients is that detailed information can be obtained. However, such samples are often not representative of the entire population of patients with disease. In this paper, we present data on psychological distress from a large representative sample of adults with different forms of heart disease including coronary heart disease (CHD), myocardial infarction (MI), and congestive heart failure (CHF). The data were obtained from the 2002 National Health Interview Survey (NHIS), which is a yearly survey conducted on a probability sample of individuals living in the US. Thus the findings are representative of the general population of adults with heart disease.
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Methods
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NHIS is a yearly interviewer-administered survey conducted by the National Center for Health Statistics and the Centers for Disease Control and Prevention. It has been performed on an annual basis since 1957 and it is currently the primary source of information on health and illness in the US.1 The NHIS provides health information on a large, representative sample of the civilian, non-institutionalized household population of the US. Therefore, the resulting data can be generalized to the community dwelling population. The multistage sampling scheme involves a state-level stratified design with oversampling of black and Hispanic populations. Each sampled person has a known non-zero probability of selection that is used to construct the sampling weight. The sampling weight and survey design features are used to construct unbiased estimates of population totals and proportions. The NHIS consists of a basic module and supplements. The basic module contains, among others, a sample adult core, which collects health-related information on a randomly selected adult in the family. The NHIS content is updated every 1015 years. Each redesign is preceded by a great deal of research on cognition and survey measurement, which is conducted at the National Center for Health Statistics. Because heart disease primarily affects older populations, the present analysis is limited to adults who are 40 years of age and older. For the 2002 data collection period, there were 36 787 eligible individuals, of which 31 044 (84.4%) agreed to be interviewed. However, after accounting for the household response rate, the overall response rate for the sample adult core interview is 74.3%.
Three self-reported heart disease diagnoses were examined: CHD, MI, and CHF. In each case, the participant was asked, Have you ever been told by a doctor or other health professional that you had...[coronary heart disease, a heart attack (also called a myocardial infarction), congestive heart failure]? For each condition, participants who reported being told that they had the condition were compared with those participants who reported having no cardiovascular condition (CHD, MI, CHF, plus angina pectoris and stroke). Also, for each condition, additional analyses were conducted for participants who reported that particular condition only and those with that condition and at least one additional condition. For example, patients with self-reported CHF were compared with patients with no self-reported cardiovascular disease (CVD) (CHD, MI, angina pectoris, or stroke). Next, participants with self-reported CHF were further classified into those with CHF only and those with CHF and either CHD, MI, angina pectoris, or stroke. The objective of these additional analyses was to determine whether additional diagnoses had an incremental association with psychological distress. The participants who self-reported each condition were asked whether they experienced the condition in the past 12 months. We conducted additional analyses to determine whether participants who experienced the condition within the past 12 months experienced greater psychological distress when compared with their counterparts who experienced the event more than 12 months ago.
Psychological distress was examined with the K6, which was developed specifically for the NHIS.2 The K6 contains six items that ask how often during the past 30 days the participant felt sad, nervous, restless, hopeless, everything was an effort, and worthless. The responses were scored from 0 to 4 on a Likert scale with ratings from None of the time to All of the time. The total scores, therefore, range from 0 to 24 and a score of 13 has been suggested as a cut-point for classifying individuals as having a serious mental illness. Serious mental illness is defined as having at least one 12-month Diagnostic and Statistical Manual of Mental Disorder diagnosis, not counting a substance-use disorder that results in serious impairment.3 The cut-point has been developed to operationalize the definition of serious mental illness; therefore, it is highly likely that many more people will have a mental disorder and will not be detected by this definition. The psychometric properties of the K6 have been examined in men and women who were sampled from the telephone directory in Boston, MA, USA, and were found to be well within the desirable range of such an instrument as demonstrated by: (i) the internal consistency reliability, measured by Cronbach's
, was 0.89; (ii) the discrimination, assessed by examining the area under the ROC curve, was 0.86; (iii) the sensitivity and specificity using the cut-point score of 13 were 0.36 and 0.96, respectively, with an overall accuracy of 0.92.3
Additional variables included in the analyses were age, gender, race/ethnicity, marital status, education, self-reported hypertension, self-reported diabetes, obesity, smoking status, alcohol intake, and physical activity level. Table 1 contains information on the coding of these variables.
Statistical analysis
Descriptive statistics were computed for the entire sample and also for individuals with and without an elevated K6 score. Then, for each heart disease condition, the proportion of participants with an elevated K6 score along with the total number of individuals in the civilian non-institutionalized population over the age of 40 with an elevated K6 score were estimated.
The primary analyses involved estimating odds ratios (ORs) for an elevated K6 score for each heart disease condition (CHD, MI, CHF) by a logistic regression model. The model contained age, gender, race/ethnicity, education, marital status, smoking, alcohol use, physical activity, diabetes, hypertension, and obesity as variables. These variables were included as potential confounders on the basis of the previous research that has linked them to both psychological distress and heart disease.46 Secondary analyses involved fitting additional models for each heart disease condition to determine the effect of additional heart disease diagnoses and the effect of experiencing the condition within the past year on the level of psychological distress. As the NHIS uses multistage sampling, all models were fit using Stata 8.0 (College Station, TX, USA) to account for the sampling design and statistical weights. In Stata, there is a procedure for estimating proportions and totals and also fitting logistic regression models when the data are obtained from a survey sample. The stratification, clustering, and statistical weights were thus accounted for in the analysis in order to obtain more accurate estimates of the parameters and standard errors. All statistical tests were two-sided and in addition to ORs, 95% confidence intervals are presented. Continuous variables in a logistic regression model must meet the assumption of linearity in the logit. This assumption was assessed for age by using the fractional polynomial procedure in Stata.
The prevalence estimates of the individual symptoms of psychological distress on the K6 were examined in each group of CVD patients. The responses were categorized into None of the time, A little of the time or Some of the time, and Most of the time or All of the time. Finally, the per cent of patients in each CVD category who reported having seen a mental health professional within the past year was estimated for patients with and without an elevated K6 score separately.
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Results
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A total of 18 336 NHIS participants were of age 40 or older. However, only 17 541 (96%) respondents had complete data for the K6 and other covariates of interest. Compared with the participants with complete data, those with missing data were slightly older (59±14 vs. 58±13 years), more likely to have less than a high school education (29 vs. 20%), be male (46 vs. 43%), non-Hispanic black or other race/ethnicity (22 vs. 16%), a never smoker (57 vs. 50%), obese (49 vs. 29%), never married (12 vs. 9%), sedentary (69 vs. 47%). Table 2 contains the descriptive statistics for the total sample and for participants with and without an elevated K6 score. Among respondents with an elevated K6 score, there were more females, individuals with less than a high school education, Hispanics and non-Hispanic blacks, obese individuals, non-drinkers, current smokers, sedentary individuals, and individuals with hypertension or diabetes.
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Table 2 Per cent distributions of select characteristics for the total NHIS sample and by elevated K6 score status
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In the US population over the age of 40 and with no CVD, the estimated prevalence of psychological distress, defined by an elevated K6 score, is 2.8%. This population estimate was calculated accounting for the sampling design and statistical weights. The population prevalence estimate and estimated total number of individuals in the US over the age of 40 with psychological distress by CVD category are presented in Table 3. Although no statistical comparisons were made, as this was not the objective of the analysis, we do note that the greatest proportion of psychological distress was estimated among participants with CHF (10%) followed by MI (6.4%) and CHD (4.1%). Within each disease category, experiencing the condition within the previous 12 months led to more psychological distress when compared with experiencing the condition more than 12 months ago; however, no formal comparisons were made to determine whether these results were statistically significant. Over 1 million individuals of age 40 or older with a history of CHD, MI, or CHF are estimated to have psychological distress.
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Table 3 Per cent distributionsa (and 95% CI) and estimates of the total number of individuals over age 40a with elevated K6 scores by CVD group
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The logistic regression results are presented in Table 4. For CHD, there was a slight increase in the odds of experiencing psychological distress; however, the result was not statistically significant (OR 1.3, 95% CI 0.91.8). The ORs associated with CHD and at least one other cardiovascular condition was also not significant in the fully adjusted model. Similar results were found when we examined the association between psychological distress and time since the last CHD episode. Self-reported MI was associated with an OR of 2.0 (95% CI 1.43.0) for psychological distress and there was little difference between the MI only and the MI plus at least one additional CVD categories. In the model that examined time since the last episode, the ORs associated with self-reported MI more than 12 months ago and within the past 12 months were 2.2 (95% CI 1.43.5) and 1.8 (95% CI 1.03.1), respectively. Self-reported CHF was associated with a three-fold increased odds of having psychological distress. The ORs for psychological distress associated with the CHF only group and with the CHF and at least one additional CVD group were both elevated (OR 3.6, 95% CI 1.58.6 vs. OR 2.9, 95% CI 1.65.1). Finally, the OR for CHF episodes within the past year was 3.4 (95% CI 2.05.9) and the OR associated with events experienced more than 1 year ago was 2.5 (95% CI 0.96.8).
To examine which symptoms of psychological distress are most common in the different CVD categories, frequency distributions were estimated and are presented in Table 5. These data are presented as descriptive statistics; therefore, no formal tests were performed on the symptoms. For all symptoms, experiencing the symptom most of the time or all of the time was more common among individuals with CHF, followed by individuals with MI and then CHD. All symptoms were more common among individuals with a CVD compared with those with no CVD.
Finally, the prevalence estimates of seeing a mental health professional within the past year were 4 and 31% for CHD patients without and with psychological distress, respectively. For participants with MI, the estimates were 5 and 34%, respectively. Among those participants with CHF, the respective prevalence estimates were 5 and 35%.
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Discussion
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The results suggest that psychological distress is a burden among participants with various heart disease diagnoses. The estimated prevalence of psychological distress, defined as an elevated K6 score, is 2.8% in US adults over the age of 40 and with no heart disease. Individuals with CHF have the highest prevalence at 10%, followed by MI (6.4%) and CHD (4.1%). The estimated total number of patients with one or more of these heart diseases who experience psychological distress is over 1 million. All the symptoms of psychological distress included on the K6 are more prevalent among respondents with one or more of the heart diseases. Thus, the findings are not limited to an unequal distribution of one or two particular symptoms. What is perhaps most alarming though, is the low prevalence of visits to a mental health professional. All patients with a diagnosis of serious mental illness should receive such services and these data indicate that only 3135% have seen a mental health professional. We should note, however, that it is possible that some of the patients who were not treated by a mental health professional were in fact treated for distress by another type of health professional. The survey does not include such questions that would have allowed us to examine other types of health professionals. There is clearly a benefit to treating psychological distress and other conditions. Denollet and Brutsaert7 examined the effect of cardiac rehabilitation on improvement in emotional distress and its ultimate effect on prognosis. They found that rehabilitation, when compared with standard care, prevented a decline in negative affect, which was consequently associated with a beneficial prognosis in CHD patients. Lacey et al.8 compared post-MI patients who received cardiac rehabilitation alone with patients who received rehabilitation plus a self-help package that included information on relaxation, exercise, and other lifestyle modifications. The supplemental package was also accompanied by interactions with a facilitator who contacted the patients during the first 6 weeks after the MI. Following the intervention, both anxiety and depression levels improved significantly greater in the intervention group compared with the control condition.
The results from the logistic regression models suggest that individuals with self-reported CHD, MI, or CHF are more likely to experience psychological distress when compared with those without CVD. It is not entirely clear why the OR associated with CHF plus at least one additional CVD was smaller compared with the OR associated with CHF only. It is possible that individuals with CHF only are more certain of that diagnosis compared with those with CHF and at least one additional condition. Some individuals in this latter group may have experienced heart failure symptoms while in the hospital with an MI or another condition; however, they were never considered true CHF cases. Such a scenario would suggest misclassification in this group.
Psychological distress has been associated with morbidity and mortality.46 Stansfeld et al.4 examined the effect of psychological distress, measured with the General Health Questionnaire (GHQ),9 on incident CHD in men and women enrolled in the Whitehall II Study, a cohort comprising based civil service employees in London. They found that psychological distress was predictive of incident CHD in men; however, in women the results were not as robust. Rasul et al.5 examined the effect of psychological distress, assessed with the GHQ, on CHD mortality using data from the Renfrew and Paisley study, which is a population based cohort study of men and women who were followed for 20 years. They found that while the prevalence of psychological distress was higher in women compared with men, it was only associated with CHD and all-cause mortality in men. A third study that also used the GHQ, although it was a shorter version of the GHQ,10 found that intermediate and high levels of distress were predictive of all-causes and heart disease mortality in a group of men and women drawn from the population.6 Clearly, from these studies there is an indication that psychological distress is predictive of heart disease. Little has been published on psychological distress following a diagnosis of heart disease. Pignalberi et al.11 did, however, examine factors associated with psychological distress in a sample of patients hospitalized with acute MI or angina and compared this group with patients hospitalized for acute trauma conditions. They found that the cardiac patients had significantly higher levels of psychological distress when compared with the controls. The present study extends the research in the area of psychological distress and heart disease by assessing the associations in a large probability sample that is obtained from the free-living US population. The present study also provides information on heart failure; whereas the previous studies examined MI and CHD only.
Table 6 contains the ORs associated with the other covariates in the fully adjusted models. Though no formal statistical tests were performed, the majority of ORs are smaller in magnitude compared with the OR associated with MI and all were smaller than the OR associated with CHF. Therefore, at least these two CVD diagnoses have a similar magnitude of association when compared with other traditional risk factors.
The main strength of this study is the large, population-based sample. The NHIS has been conducted annually since 1957 and data are obtained each year on a sample that is representative of the US civilian, non-institutionalized population. In 2002, the response rate was 74.3%, which is an excellent response rate for population-based surveys. A second strength of this study was the use of the K6, which was developed for use in the NHIS by experts in the field of psychological measurement. The questionnaire has good psychometric properties and, hence the classification of serious mental illness based on the K6 score is valid.
One limitation to this study is that the measure of psychological distress using the K6 cut-point of 13 leads to a low sensitivity (36%). This suggests that not all individuals with serious mental illness are being detected. This cut-point was, however, chosen to balance the false negatives and false positives.3 A second disadvantage in using the K6 relates to the fact that it is a non-specific measure of psychological distress. The classification of serious mental illness that can be made with the K6 is not the result of experiencing symptoms for just one mental health disorder.
The self-reported nature of the data is another limitation to the study. All of the heart disease data are based on the assumption that the participants have been told that they either do or do not have the condition by a healthcare professional. However, the self-report strategy of data collection permits a survey sample sufficiently large to be representative of the entire US population. Accordingly, the NHIS is the primary source of health data in the US and it has been conducted annually since 1957 with regular updates of the design and content. Several investigations have been performed to assess the validity of self-reported heart disease, and in general the agreement is good.1216 Bergmann et al.12 examined the accuracy of self-reports of ischaemic heart disease in the National Health and Nutrition Examination Survey cohort, a study that is similar in nature to the NHIS, but it has an added health examination. They found that self-reports of hospitalization for ischaemic heart disease was 84% and the accuracy was positively associated with the level of education. However, in general, accuracy was not related to age, gender, race, alcohol use, or smoking. Self-reported conditions were also examined for accuracy in the Cardiovascular Health Study, a cohort of adults 65 years and older.13 They found agreement between self-reports of MI and medical records in 77% of men and 65% of women. Among the participants who reported no previous MI, only 4% of men and 3% of women had an evidence of a previous MI on an electrocardiogram. From these and other studies it is clear that self-reported heart disease agrees well with disease status confirmed by a clinician.
A second limitation to the study is that laboratory data are not collected in the NHIS. Therefore, we could not examine the severity of heart disease, functional class for CHF, or other biological measures such as plasma cholesterol.
Clearly, individuals with heart disease are suffering from higher than normal levels of psychological distress. These findings imply that psychological stress is among the important comorbidities that must be taken into consideration in the management of CVD. Other investigations have demonstrated a link between psychological distress and morbidity and mortality. Taken together, these findings provide the impetus for future investigations that assess the role that a medical and mental health care professional intervention may have in altering these outcomes when targeted at this distress. These data also suggest that only 3135% of patients with psychological distress and CVD have seen a mental health professional within the past year. We recommend that clinicians make screening for psychological distress a component of the routine evaluation of the patient with CVD. The screening tool should be used as a means to alert the clinician that the patient may have a need for psychological care and serve as a basis for referral to mental health professionals.
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Acknowledgement
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We acknowledge NIH for the proposal grant Paradigm Shifts in Clinical Ischemia Detection (NIH HL04208-02).
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References
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- CDC. 2002 National Health Interview Survey (NHIS) Public Use Data Release. Division of Health Interview Statistics, National Center for Health Statistics: Hyattsville, MD. December 2003.
- Kessler RC, Andrews G, Colpe LJ, Hiripi E, Mroczek DK, Normand SLT, Walters EE, Zaslavsky AM. Short screening scales to monitor population prevalences and trends in non-specific psychological distress. Psychol Med 2002;32:959976.[CrossRef][ISI][Medline]
- Kessler RC, Barker PR, Colpe LJ, Epstein JF, Gfroerer JC, Hiripi E, Howes MJ, Normand SLT, Manderscheid RW, Walters EE, Zaslavsky AM. Screening for serious mental illness in the general population. Arch Gen Psychiatry 2003;60:184189.[Abstract/Free Full Text]
- Stansfeld SA, Fuhrer R, Shipley MJ, Marmot MG. Psychological distress as a risk factor for coronary heart disease in the Whiethall II Study. Int J Epidemiol 2002;31:248255.[Abstract/Free Full Text]
- Rasul F, Stansfeld SA, Hart CL, Gillis CR, Smith GD. Psychological distress, physical illness and mortality risk. J Psychosom Res 2004;57:231236.[CrossRef][ISI][Medline]
- Robinson KL, McBeth J, MacFarland GJ. Psychological distress and premature mortality in the general population: a prospective study. Ann Epidemiol 2004;14:467472.[CrossRef][ISI][Medline]
- Denollet J, Brutsaert DL. Reducing emotional distress improves prognosis in coronary heart disease: 9-year mortality in a clinical trial of rehabilitation. Circulation 2001;104:20182023.[Abstract/Free Full Text]
- Lacey EA, Musgrave RJ, Freeman JV, Tod AM, Scott P. Psychological morbidity after myocardial infarction in an area of deprivation in the UK: evaluation of a self-help package. Eur J Cardiovasc Nurs 2004;3:219224.[CrossRef][Medline]
- Goldberg DP. Detecting Psychiatric Illness by Questionnaire. Maudsley Monograph 21. London: Oxford University Press, 1972.
- Goldberg DP, Gater R, Sartorius N, Ustun TB, Piccinelli M, Gureje O. The validity of two versions of the GHQ in the WHO study of mental illness in general health care. Psychol Med 1997;27:191197.[CrossRef][ISI][Medline]
- Pignalberi C, Patti G, Chimenti C, Pasceri V, Maseri A. Role of different determinants of psychological distress in acute coronary syndromes. J Am Coll Cardiol 1998;32:613619.[Abstract/Free Full Text]
- Bergmann MM, Byers T, Freedman DS, Mokdad A. Validity of self-reported diagnoses leading to hospitalization: a comparison of self-reports with hospital records in a prospective study of American adults. Am J Epidemiol 1998;147:969977.[Abstract]
- Psaty BM, Kuller LH, Bild D, Burke GL, Kittner SJ, Mittelmark M, Price TR, Rautaharju PM, Robbins J. Methods of assessing prevalent cardiovascular disease in the Cardiovascular Health Study. Ann Epidemiol 1995;5:270277.[CrossRef][Medline]
- Colditz GA, Martin P, Stampfer MJ, Willett WC, Sampson L, Rosner B, Hennekens CH, Speizer, FE. Validation of questionnaire information on risk factors and disease outcomes in a prospective cohort study of women. Am J Epidemiol 1986;123:894900.[Abstract]
- Lampe FC, Walker M, Lennon LT, Whincup PH, Ebrahim S. Validity of a self-reported history of doctor-diagnosed angina. J Clin Epidemiol 1999;52:7381.[CrossRef][ISI][Medline]
- Bush TL, Miller SR, Golden AL, Hale WE. Self-report and medical record report agreement of selected medical conditions in the elderly. Am J Public Health 1989;79:15541556.[Abstract]
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