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ORIGINAL ARTICLES |
From the Douglas Hospital Research Centre (N.S.), Clinical Research Division, McGill University, Montreal, Quebec, Canada; the Robert Koch-Institute (W.T.), Berlin, Germany; and the Research Unit for Public Mental Health (N.S., J.K.), Clinic for Psychosomatic Medicine and Psychotherapy, Heinrich-Heine-University, Duesseldorf, Germany.
Address correspondence and reprint requests to Norbert Schmitz, PhD, Douglas Hospital Research Centre, McGill University, 6875 LaSalle Boulevard, Montreal, Quebec, H4H 1R3, Canada. E-mail: norbert.schmitz{at}douglas.mcgill.ca
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ABSTRACT |
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Methods: The analysis was based on data from 4149 respondents, ages 18 to 65 years, from the German National Health Interview and Examination Survey, a nationally representative multistage probability survey conducted from 1997 to 1999. Mental disorders were assessed by a modified version of the Composite International Diagnostic Interview. Blood pressure was measured during the medical examination by a health examiner.
Results: There was no general association between awareness of hypertension and affective, anxiety, and substance abuse/dependence disorders. Men with acknowledged but untreated hypertension more often experienced affective and substance abuse/dependence disorders than men with treated hypertension. These relationships were stable after adjustment for sociodemographic and clinical characteristics.
Conclusions: Our results suggest that it is important to distinguish between treated and acknowledged but untreated hypertension when evaluating the associations between mental disorders and hypertension.
Key Words: hypertension • survey • depression • substance dependence
Abbreviations: BMI = body mass index; CI = confidence interval; CIDI-S = Composite International Diagnostic Screener; CIDI = Composite International Diagnostic Interview; CVD = cardiovascular diseases; DBP = diastolic blood pressure; GHS = German National Health Interview and Examination Survey; OR = odds ratio; SBP = systolic blood pressure.
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INTRODUCTION |
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Several studies performed in a variety of countries have shown that blood pressure values are satisfactorily controlled by treatment in only a small fraction of the hypertensive population (4–10). A recent study in the United States suggests that approximately one third of persons in the general population who have hypertension are unaware of it, whereas 17% were aware of their condition but were not being treated and only 23% were taking medication that controlled their blood pressure (7). Similar results were found in an Australian survey; approximately half the survey participants with hypertension were untreated (8). Hypertension treatment has been found to be lower in European countries than in the North American countries (9).
However, data on factors associated with hypertension awareness and treatment in the general population are sparse, although this information is critically important as a scientific basis for developing strategies for appropriate hypertension management in the community.
Medical patients may be noncompliant for many reasons, including their disbelief in the efficacy of treatment (11), the presence of barriers such as adverse effects, and lack of support from family members (12). Additionally, there is some evidence that psychological distress and lifestyle variables are associated with noncompliance, too. For example, in a recent meta-analysis, DiMatteo and colleagues (13) found a substantial relationship between depressive symptoms and noncompliance.
Briganti et al. (8) found that current smoking and excessive alcohol intake were significantly associated with lack of hypertension treatment in the Australian Diabetes, Obesity and Lifestyle Study.
The coexistence of mental disorders with medical illness is a topic of considerable research interest. It is well established now that mental disorders may complicate the treatment of chronic medical conditions (14,15). However, little is known about the association between mental disorders and asymptomatic chronic diseases. Therefore, the aim of the present study was to evaluate the relationship between mental disorders and awareness and treatment of hypertension in a community sample. We took advantage of the large representative sample of the German general population studied in the German National Health Interview and Examination Survey (GHS) (16,17) to explore the relation between treatment of hypertension and affective, anxiety, and substance abuse/dependence disorders. The a priori hypothesis was that there would be higher prevalence rates of psychiatric disorders for subjects with acknowledged but untreated hypertension than for subjects with treated hypertension.
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RESEARCH DESIGN AND METHODS |
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The German National Health Interview and Examination Survey had 7124 participants, the overall rate of response in the main survey was 61.5%, and the rate of response in the second stage (the psychiatric interview included 4181 persons) was 87.6%. Nonresponse was mainly the result of refusal to participate and an inability to reach selected respondents. The rates of nonresponse in the second stage did not differ significantly between screen-negative and screen-positive respondents from the main survey (18). All subjects voluntarily participated in the study.
After a complete description of the study was provided, written informed consent was obtained from the participants.
The survey was approved by the Institutional Review Boards of the Robert-Koch-Institute, Germany.
Assessment
Blood pressure (mm Hg) was measured three times during the medical examination by a health examiner while the participant was sitting after 3 minutes of rest (19). The mean of the second and third readings was reported. Hypertension was defined as an average systolic blood pressure 
140 mm Hg or an average diastolic blood pressure 90 mm Hg and/or self-reported current treatment for hypertension with antihypertensive medication. We defined hypertension status according to the criteria used by Burt et al. (20) (Table 1).
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Chronic illness was assessed in the present study by a response of "yes" or "no" to the question, "Do you have or did you ever have the following diseases: diabetes, cardiovascular disease, kidney disease, asthma, or cancer?"
To assess disability and reduction in work productivity, the subjects were asked how many days in the last year they were unable to work or to carry out normal, everyday activities. For assessing medical service utilization, respondents were asked about their use of medical outpatient services during the previous 12 months. Ambulatory office visits were defined as primary care visits and medical specialty visits. The range of medical specialty areas included internal medicine, general surgery, gynecology, ophthalmology, orthopedics, otolaryngology, urology, dermatology, radiology, neurology, psychiatry, and psychotherapy (21). Cigarette smoking status was determined by self-report. Participants were classified as nonsmokers, former smokers, or current smokers.
The survey used a two-stage design for the identification of mental disorders. At the first stage, all participants completed the Composite International Diagnostic Screener (CID-S) (22) for mental disorders. Subjects aged 65 years and younger who screened positive and a 50% random sample of those who screened negative were selected for stage 2 of the survey, in which 4181 participants were administered the full Composite International Diagnostic Interview (M-CIDI) (24) for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (23) disorders by clinical interviewers. The mental health interviews took place within 2 weeks of the main survey. The interviews were conducted by 24 trained interviewers, most of whom had already worked in other CIDI studies during the previous 5 years. The diagnoses in the present study included affective disorders (major depression disorder, dysthymic disorder, and bipolar disorders), anxiety disorders (panic disorder, agoraphobia, social phobia, specific phobia, and generalized anxiety disorder), and substance abuse/dependence disorders.
Only current disorders occurring during the past 4 weeks were considered in the present study.
The data of the mental health supplement were released for public use in 2000 (24).
Statistical Analysis
We used descriptive statistics to summarize the study variables among all categories of hypertension. Continuous variables were compared with use of a t test for independent groups; categorical variables were compared with use of the chi-squared test. Univariate analyses were performed to identify the association of sociodemographic and clinical characteristics with hypertension status. To evaluate lack of treatment of hypertension, we compared subjects with acknowledged but untreated hypertension to subjects with treated hypertension, regardless of hypertension control.
Multiple linear regression models were used to evaluate the relationship between mental disorders and blood pressure, whereas logistic regression models were used to evaluate relationships between mental disorders and lack of treatment of hypertension. Odds ratios were calculated in the multivariate models and 95% confidence intervals (CIs) were calculated using maximum likelihood methods. In the first, we adjusted for factors that may confound the association between mental disorders and blood pressure, including age, gender, socioeconomic status, marital status, body mass index, chronic disease, smoking status, and blood pressure treatment. We adjusted for additional factors such as medical service utilization and disability (number of days unable to work) when evaluating the association between mental disorders and hypertension treatment.
The Hosmer-Lemeshow goodness-of-fit criterion was used to determine the adequacy of the logistic regression models. Collinearity was assessed by calculating tolerance levels and variance inflation factors (VIF) for each predictor variable (25).
All data in the present study were weighted by demographic characteristics (age, gender, and geographical location). Subjects assessed for mental disorders were additionally weighted by selection probabilities (screen-negatives received twice the weight of screen-positives) as a result of the two-stage sampling design for the mental health supplement.
Analyses were performed using Stata (26) software that included commands for the analysis of complex survey data.
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RESULTS |
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The overall prevalence of hypertension in the sample was 39.8%. Men were more likely than women to experience hypertension (46.8% and 33.1%, respectively). In the present sample, only 40% of the hypertensive subjects were aware of their elevated blood pressure status, and 68% of these individuals were taking pharmacological treatment for the condition.
Data on demographic and clinical characteristics according to category of hypertension are presented in Tables 2 and 3.
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The treatment of hypertension was associated with demographic and clinical characteristics, too.
Subjects with acknowledged but untreated hypertension were younger, more often male, more often current smokers, and were less frequent users of health care than subjects with treated hypertension. There was little difference in the self-reported number of days unable to work or carry out everyday activities between the two groups. Nearly half of the subjects with treated hypertension reported at least one other chronic disease. The number of chronic diseases was significantly lower for the subjects with acknowledged but untreated hypertension.
In contrast to the demographic and clinical characteristics, we found similar mean blood pressure values for those with and without blood pressure treatment.
Table 4 shows blood pressure values for those with and without mental disorders. We found no general association between mental disorders and systolic and diastolic pressure after controlling for potentially confounding variables. Although not significant (p = .06), men with affective disorders had lower systolic blood pressure values than men without mental disorders. In contrast, men with substance abuse/dependence disorders had a higher diastolic blood pressure than men without mental disorders (p = .06).
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Prevalence rates and adjusted odds ratios of the mental disorders according to hypertension status and gender are examined in Table 5. Affective, anxiety, and substance dependence disorders were not associated with awareness of hypertension (treated and untreated). Although subjects who were unaware of their hypertension had lower prevalence rates of affective and anxiety disorders in comparison to those who were aware of their hypertension, the associations were not significant in the logistic regression models after controlling for potentially confounding factors (95% confidence intervals of the odds ratios for affective and anxiety disorders included 1).
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Affective and anxiety disorders per se were not associated with treatment of hypertension. However, a higher prevalence of affective disorders was observed for men with acknowledged but untreated hypertension. A similar association was observed for substance abuse/dependence disorders; men with untreated hypertension had higher prevalence rates of substance abuse/dependence disorders than men with treated hypertension. The associations remained significant after controlling for age, socioeconomic status, marital status, chronic diseases, smoking, and medical service utilization; men with untreated hypertension were more likely to experience affective and substance dependence disorders (odds ratios: 6.03 and 4.55, respectively) than those with treated hypertension.
In contrast, we found no substantial associations between mental disorders and hypertension treatment for women, and we did not find an association between anxiety disorders and hypertension treatment for both men and women.
When we compared treated hypertension with unknown hypertension, we found a similar association; men but not women with treated hypertension were less likely to experience affective and substance dependence disorders than those with unknown hypertension. Furthermore, men with treated hypertension were less likely to experience affective disorders than those without hypertension.
There was a strong relationship between chronic diseases and current affective and substance abuse/dependence disorders in men with untreated hypertension. More than half (59%) of the men with untreated hypertension and affective or substance abuse/dependence disorders had at least one other chronic disease. Similar to our other findings, a different association was found in women; most of the women with untreated hypertension and affective or substance abuse/dependence disorders (72%) did not have a chronic disease.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONRESEARCH DESIGN AND METHODSRESULTSDISCUSSIONNOTESREFERENCES |
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Our analysis yielded three important associations regarding the factors underlying treatment and awareness of hypertension: there was no general association between blood pressure and mental disorders; men with acknowledged but untreated hypertension more often experienced affective and substance dependence disorders than men with treated hypertension; and lack of awareness was associated with better health status (chronic conditions, disability).
Prospective studies that have examined the relationship of depressive or anxiety symptoms with blood pressure have been characterized by mixed results. Some studies found an association (27) and others suggested none (28). Although we did not find a general association between blood pressure and mental disorders, our findings do not negate the possibility that symptoms of depression and anxiety are risk factors for hypertension.
Regarding hypertension treatment, our results are consistent with other studies that have examined the association between hypertension treatment and smoking and alcohol intake. Briganti et al. (8) found that male sex, younger age, not being obese, insufficient physical activity, current smoking, and excessive alcohol intake were significantly associated with untreated hypertension compared with treated hypertension. Our results suggest that substance abuse and dependence, which are more severe forms of smoking and alcohol intake, were associated with lack of hypertension treatment, too. In the present sample, most of the subjects with current substance abuse/dependence disorders had alcohol or nicotine dependence disorders. As a conclusion, programs to improve treatment of hypertension should not only focus on lifestyle variables like smoking and alcohol, but they should also include the identification and treatment of substance abuse and dependence disorders.
Additionally, our results are consistent with other studies regarding depression and anxiety symptoms. In a recent meta-analysis, DiMatteo et al. (13) found a strong covariation of depression and medical noncompliance in medical patients. The odds for being noncompliant with medical treatment recommendations were three times greater for depressed patients in comparison to nondepressed patients. Similar to our results, the authors did not find an association between anxiety and noncompliance.
The lack of an association between anxiety disorders and hypertension in our cross-sectional study is unlikely to be a result of insufficient statistical power. Moreover, this result suggests that there is no general association between current anxiety disorders and hypertension, although it is possible that anxiety has a predictive value in the development of hypertension. Higher prevalence rates of anxiety disorders have been reported for subjects with other chronic diseases (e.g., diabetes) (29,30). However, hypertension is largely an asymptomatic disease, and subjects with hypertension may have not more anxiety symptoms than subjects without hypertension because they may not be worrying about the future and the possibility of serious complications of their hypertension.
The significant association between depression and hypertension treatment in men suggests that depression has a moderating effect, because depression is known to decrease rates of adherence to medications and self-care regimens in patients with chronic diseases (13). Depression often involves an appreciable degree of hopelessness, and compliance might be difficult or impossible for a patient who holds little optimism that any action will be worthwhile. However, we cannot determine whether affective disorders causes noncompliance or noncompliance causes affective disorders. Causal conclusions would require a causal modeling from longitudinal data. As pointed out by DiMatteo et al. (13), it is possible that a "feedback loop" exists such that depression causes noncompliance with medical treatment and noncompliance further exacerbates depression so that a clinical focus on both might be essential. Nevertheless, depressive symptoms may be a modifiable risk factor for poor compliance with antihypertensive medications.
Further research is needed to evaluate the associations between mental disorders and hypertension.
Numerous studies have produced evidence that patients with depression have an increased risk of developing cardiovascular disease (31). Depression in untreated hypertension might increase risk of developing cardiovascular disease.
An important point is that the associations of hypertension treatment and mental disorders were found only in men and not in women. We can only speculate about the reasons for these gender-specific associations. A high proportion of men with untreated hypertension and mental disorders had at least one chronic disease. It is possible that chronic diseases play a key role in the development of affective disorders as a result of limited functioning, feelings of hopelessness, and impaired energy. Furthermore, it is also possible that the lower prevalence of affective/substance abuse disorders in men with treated hypertension is related to the fact that these men have been successfully treated for hypertension because of closer physician surveillance. Additionally, the presence of other chronic diseases might have forced them to relinquish substance abuse.
When evaluating the results of the present study, it should be remembered that physicians play a major role in the identification and treatment of hypertension in their patients. However, definitions of abnormal or treatable blood pressures have changed. Until recent years, isolated systolic hypertension was defined as a systolic blood pressure of more than 160 mm Hg (32). This term has been redefined as a systolic blood pressure of more than 140 mm Hg (33). There are still many physicians who do not believe that cardiovascular risk is increased until systolic blood pressures rise above 150 to 160 mm Hg (34). Additionally, it is possible that physicians underestimate blood pressure office readings because they believe that the office blood pressure readings are usually higher than outside readings (white coat effect).
The present findings are constrained by several limitations. First, the data are cross-sectional and although the German National Health Interview and Examination Survey are population-based, we are unable to longitudinally determine the relationship among hypertension, health status, and mental disorders. Second, subjects aged 66 years and above were excluded from the second stage of the survey as a result of psychometric shortcomings of the Composite International Diagnostic Interview in older populations. Therefore, we can draw no conclusions about the association between mental disorders and hypertension in older populations. Third, blood pressure measurements were obtained at a single point in time. Although blood pressure was measured by taking the average of two separate measurements obtained under the same standardized conditions, it is possible that the prevalence of untreated hypertension may have been overestimated. Systolic blood pressure has been shown to decrease as much as 10 mm Hg and diastolic blood pressure as much as 5 mm Hg over 8 weeks in patients with untreated hypertension (35). Therefore, it is possible that our untreated sample include patients with white coat hypertension. Other potential sources of bias in the reported estimates of hypertension prevalence include possible blood pressure control by nonpharmacological means (diet and exercise). Additionally, participants who have been told that they have hypertension but are not receiving medications and have blood pressure below the 140/90 mm Hg cut points are not counted as hypertensive. Also, medication type was not confirmed. We cannot exclude that subjects may have been using medications that lower blood pressure for other indications.
Fourth, we have no information if subjects with acknowledged but untreated hypertension refused hypertension treatment or if their physicians never offered treatment to them. However, we assume that most of these subjects were offered treatment, because their hypertension was diagnosed by a health professional.
In summary, untreated hypertension is a significant public health problem. Inappropriate undertreatment of hypertension represents a missed opportunity to reduce the burden of cardiovascular diseases. Previous studies have shown that a lot of physicians fail to take aggressive steps in lowering the blood pressure if the patient is simply feeling fine (36,37). However, the present study suggests that mental disorders may be barrier to hypertension treatment, too. Therefore, a more aggressive treatment of hypertension, modification of lifestyle variables as well as an early identification/treatment of mental problems might improve the management of hypertension.
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NOTES |
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Received for publication March 14, 2005; revision received October 7, 2005.
DOI:10.1097/01.psy.0000204883.77284.6b
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  J. Sareen, F. Jacobi, B. J. Cox, S.-L. Belik, I. Clara, and M. B. Stein Disability and poor quality of life associated with comorbid anxiety disorders and physical conditions. Arch Intern Med, October 23, 2006; 166(19): 2109 - 2116. [Abstract] [Full Text] [PDF]
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