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Applied Psychophysiology and Biofeedback, Vol. 31, No. 1, March 2006 ( C 2006)DOI: 10.1007/s10484-006-9004-8 The Efficacy of Behavioral Treatments for Hypertension
Wolfgang Lindenand Janine V. Moseley
Evidence is reviewed for the efficacy of behavioral treatments for hypertension. The formatchosen here is a review of reviews given that numerous consensus committee reports andquantitative reviews on the topic have been published. Extensive evidence from over 100randomized controlled trials indicates that behavioral treatments reduce blood pressure(BP) to a modest degree, and this change is greater than what is seen in wait-list or otherinactive controls. Effect sizes are quite variable. The observed BP reductions are muchgreater when BP levels were high at pre-test, and behavioral studies tend to underestimatepossible benefits because of floor effects in their protocols. Blood pressure measured in theoffice may be confounded with measurement habituation. Multi-component, individualizedpsychological treatments lead to greater BP changes than do single-component treatments.
Among biofeedback treatments, thermal feedback and electrodermal activity feedback farebetter than EMG or direct BP feedback, which tend to produce null effects. There continuesto be a scarcity of strong protocols that properly control for floor effects and potentialmeasurement confounds. KEY WORDS: hypertension; blood pressure; outcome; treatment; efficacy.
ABBREVIATIONS
Given a population prevalence of 13–30% for hypertension, the control of elevated BP is the most frequent activity of medical practitioners. With growing levels of education andeasier access to medical knowledge through electronic information channels, patients havebecome better-informed consumers and want choices in treatment. Although there is clearevidence that antihypertensive medications are useful in controlling high BP and reduce 1Psychology, The University of British Columbia, 2136 West Mall, Vancouver, BC, Canada V6T 1Z4.
2Address all correspondence to Dr. Wolfgang Linden, Psychology, The University of British Columbia, 2136 West Mall, Vancouver, BC, Canada V6T 1Z4; e-mail: [email protected].
1090-0586/06/0300-0051/1 C 2006 Springer Science+Business Media, Inc.
Linden and Moseley
the incidence of stroke and infarction (JNC VII, Tomiak & Gentleman, therealso is a consensus that long-term drug treatment can be expensive and that side effectsthreaten patients’ adherence to drug prescriptions (Kaplan, Kawachi & Malcolm,In addition, the benefits of drug treatments as observed in controlled trials do nottranslate into similarly strong benefits in the entire treated hypertensive population: For allbut the most severely hypertensive patients, treatment was associated with increased ratherthan decreased mortality rates in a clinical sample of 21,314 patients followed for 10 years(Thuermer, Lund-Larsen, & Tverdal, Growing interest in non-pharmacological treatments for hypertension led to the com- position of two expert panels that provided consensus positions on the effectiveness ofnon-pharmacological approaches in order to guide clinical practice, health care policymaking, and future research (The Canadian Consensus Conference on non-pharmacologicalapproaches to the management of high blood pressure, The Joint National Commit-tee on Detection, Evaluation, and Treatment of High Blood Pressure, Both panelsreported that psychological interventions, in the form of relaxation training and stress man-agement, had not been subjected to rigorous clinical trials and that it was premature torecommend these methods.
Subsequent reviews have criticized these consensus reports for having reviewed only a fraction of the already available, published data thus providing an incomplete and mis-leading picture of the evidence (Jacob, Chesney, Williams, Ding, & Shapiro, Linden,Linden & Chambers, McGrady & Linden, Spence, Barnett, Linden,Ramsden, & Taenzer, In addition to criticizing such selective sampling practices,these reviewers have argued that a comprehensive review needs to un-tease reported resultswith regard to critical differences in treatment type, measurement method, and patient selec-tion criteria given that protocol differences have been shown to critically affect observableoutcomes (Eisenberg et al., Linden, Linden & Chambers, In this “review of reviews,” all available data will first be presented as a function of the different types of possible interventions and their respective, possibly differential, outcomes.
Means and effect sizes [Cohen’s d = (mean 1 – mean 2)/SD] are reported wherever possible.
As per convention, a d = .2 will be considered small, d = .5 as moderate, and d = .8 orgreater as a large effect. Next, evidence is presented that reporting of results organizedonly around choice of treatment technique, in the absence of a critical evaluation of theprotocols themselves, can severely mislead readers in judging the true possible effectsof psychological therapies. The discussion will illustrate which study features lead tooverestimation and which can lead to underestimation of potential benefits of psychologicaltreatments. For the purpose of this review, all psychological/behavioral treatments forhypertension will be considered psychophysiological in nature because (a) their target is tochange a physiological parameter (blood pressure), and (b) even if biofeedback devices arenot involved, the treatments have distinct psycho-somatic/psycho-physiological rationales.
We collected all available consensus and quantitative review papers on psychological or behavioral treatments of hypertension using computer literature searches (using MedLineand PsychLit) and via search of the files of the first author who has done extensive workin this area. The search parameters were: (1) Studies published during 1990 or later (given The Efficacy of Behavioral Treatments for Hypertension
the diligence of Jacobs et al.’s literature search up to 1991), and (2) use of combinations ofthe terms: “treatment,” “outcome,” “effectiveness,” “reviews,” “biofeedback,” “stress man-agement,” “psychological therapy,” “relaxation,” “meditation.” In addition, any secondarysources identified by the first method were tracked. This resulted in a pool of four consen-sus reports (JNC-VII, The Canadian Consensus Conference on non-pharmacologicalapproaches to the management of high blood pressure, The Joint National Commit-tee on Detection, Evaluation, and Treatment of High Blood Pressure, Spence et al.,and eight quantitative reviews (Devine & Reifschneider, Eisenberg et al.,Jacob et al., Kaufmann et al., Linden & Chambers, Nakao, Yano,Nomura, & Kuboki, Ward, Swan, & Chesney, Yucha et al., Note that noquantitative review differentially reported results for office versus home versus ambulatoryBPs. We attribute this reporting pattern to the fact that almost all studies summarized inthe reviews used exclusively office measures. Therefore, the reliability and validity disad-vantages associated with office measures are equally applicable to the interpretation of allthese reviews (JNC VII, The various reviews published and summarized here do notprovide additive, independent results of different trials. To a large degree (estimated to be2/3 of all reviewed studies; Spence et al., these reviewers are analyzing and reportingon the same studies, with however, varying selection criteria. Obviously, the more recentlypublished trial results could not have been available to earlier reviews.
Nakao et al. reported the absolute BP changes from only those studies that had used a pre-test inclusion criterion of 140/90 mmHg or greater at pre-treatment; as such,these authors acted in synchrony with their own report of powerful effects of level of pre-treatment BP on extent of change following treatment. In order to permit easy comparison,we computed (wherever possible) the effect size d for various treatment effects. In somecases, the reviews provided means but not standard deviations for BP and we estimated thecorresponding effect sizes by using a fixed set of numbers as substitute standard deviations.
The substituted values reflect the average standard deviations for the pre- and post-treatmentoffice BP values of all patients in the Linden, Lenz, and Con trial. These valueswere 9.8 for systolic BP and 8.4 for diastolic BP, and these figures are consistent with ourexperience of typical variation in BP data across various studies.
BP Reduction as a Function of Chosen Treatment Technique
The aggregation of different treatment techniques into clusters of conceptually similar approaches, requires a brief review of the rationale for psychological interventions in orderto avoid comparing methods with each other that are critically dissimilar. Some of thedissatisfaction with psychological interventions for hypertension stems from the fact thatit has been difficult to untangle technique-specific effects in psychotherapy from non-specific treatment effects (like hope or the quality of the therapeutic relationship). Thereis no widely accepted model of how psychological factors can directly “cause” high BP,and treatment rationales are not always clearly linked to underlying pathophysiology (fora discussion see Linden, or Gerin et al., Consistent with research findingsthat link stress to hypertension via elevated sympathetic tone and vagal dysregulation(Gerin et al., Grossman, Watkins, Wilhelm, Maolakis, & Lown, Sakakibara,Takeuchi, & Hayano, psychological treatments are designed to reduce BP byreducing stress and arousal. This is attempted via two different strategies. One approach Linden and Moseley
is to emphasize physiological arousal reduction and autonomic balance through relaxationtraining, meditation, and/or biofeedback, all of which are designed to improve a person’sautonomic, self-regulatory skills. Such methods can be taught in a standardized, manual-driven fashion, and one can package two or more methods together (for example relaxationand temperature feedback are often taught together; Jacob et al., A second approach isto conceive of stress as a multi-step process involving triggers, coping behaviors, cognitions,and physiological stress responses (Linden, that may require the teaching of a broadarray of problem-solving skills. This more complex approach precludes strict adherenceto a manual. Research using this second strategic approach targets deficient cognitive andbehavioral stress coping skills and requires more individually tailored, multi-componentinterventions because the presumed critical skills deficits are not likely the same across allhypertensive patients nor are the patients’ stimulus environments presumed to be the same.
The second approach also requires a higher level of skill and more training in psychologicaltherapies for the therapist.
We are first reporting here a description of available reviews with outcomes expressed as raw mean changes and as effect sizes d for (a) pre–post behavioral treatment comparisons,and then (b) pre–post versus no treatment or wait-list control comparisons (Table Positivesigns associated with either means or effect sizes reflect increases in BP and negative signsreflect reductions in BP (i.e., improvements). Not all cells in this table are filled because thereported outcome parameters vary across different reviews, and there is also much varietyin how authors clustered intervention types into supposedly similar groups.
The data in Table indicate that raw mean changes from pre- to post-test range from slight increases in BP due to treatment (+3.6 mmHg SBP and +2.6 mmHg DBP), todecreases of as much as −14.1 mmHg SBP and −11.1 mmHg DBP. The correspondingeffects sizes range from d = +.37 and +.27 to d = −1.43 and −1.32, SBP and DBP.
These numbers indicate that psychological interventions are highly variable in their potentialto reduce BP and that some interventions are useless or even counterproductive. Thegreatest reported BP reductions, if accepted uncritically, would suggest that psychologicaltreatment is readily comparable to the effects of drug treatment (Linden & Chambers,These summary data, however, reveal ample variation in outcomes that make itworthwhile to look for consistency in the results about comparative efficacy of differenttechniques. Nevertheless, drawing differential conclusions about technique-specific effectsis handicapped by the fact that different reviewers use different ways of labeling andclustering techniques into groups.
The greatest variation in outcomes for techniques, which appear similar at first, is found among biofeedback interventions. All biofeedback protocols share a similar rationale;namely that skill at autonomic self-regulation can be enhanced with the simultaneousfeedback of a biological signal that reflects vascular flow, muscular relaxation, and/orsympathetic activation. Interestingly, the type of biofeedback that appears to most directlytarget the intended endpoint, namely BP biofeedback, is consistently the least effective—cf., Jacob et al. Ward et al. and Yucha et al. A similar failureto reduce BP is reported for muscle tone biofeedback (Yucha et al., Thermal andelectrodermal activity biofeedback are consistently the most effective types of biofeedback,which is intriguing because neither of these approaches directly teaches patients to changethe ultimate endpoint, namely BP. Relaxation and meditation effects also vary greatlyacross different reviews; at times meditation is reported as more effective than relaxation(Eisenberg et al., Ward et al., but the reverse is found as well (Jacobs et al., The Efficacy of Behavioral Treatments for Hypertension
− − − − 27 15 − − − − − − − − 1 − − − − − − 1 1 − − − − − − − − − + + − − − − − − − − − − − − − − − − − − − ecreases Linden and Moseley
and the associated effect sizes range from +.37/ +.26 to −.66/ −1.06 (SBP/DBP).
Hence, to date there is no clear evidence that relaxation differs from meditation in itseffect on BP, nor is there a consistent picture of the effects of even the same method. Thisfinding parallels with observed similarities in relaxation versus meditation outcomes forother endpoints such as stress and anxiety (Linden, p. 124).
There also is a pattern across multiple reviews (Jacob et al., Linden & Chambers, that (1) technique combinations are more effective than single-technique applica-tions, (2) ‘stress management’ (which usually is a multi-technique intervention; see Ong,Linden, and Young, produces stronger effects than simple relaxation or biofeedbackinterventions, and (3) individualized interventions produce significantly stronger effectsthan standardized treatments (Linden & Chambers, In order to ultimately make clinical recommendations based on reviews, it will be important to separate conclusions about effectiveness of different methods relative to eachother from absolute changes. We posit that the absolute outcome effect sizes and raw meanchanges in BP levels are particularly important for clinical practice recommendations. Crit-ical protocol variations in BP levels at treatment entry and different measurement choices(further discussed later) have no known effect on the comparison of relative differencesof varying techniques with each other because almost all reported studies share the sameweaknesses, namely low pre-treatment BP levels and a predominant choice of BP officemeasures. The effects of these protocol weaknesses are therefore a constant in these re-views. For this reason, and in light of the fairly consistent findings reported in Table weconclude that multi-component treatments and individualized treatments are more effec-tive than single-technique interventions. However, we warn against rash acceptance of theobserved absolute changes described in these reviews (see Table as truly reflecting whatpsychological treatments with different selection and measurement protocols can ultimatelyproduce.
Outcome Differences as a Function of Measurement Choices and Trial Design
There is a considerable body of evidence suggesting that the choice of BP measure- ment protocol greatly affects the observed treatment effects (Eisenberg et al., Jacobet al., One critical distinction is where and how often BP is sampled (i.e., physi-cian office versus at home versus ambulatory), who measures it (i.e., physician, nurse,patient), how many samples are taken, and at what intervals samples are taken. The rec-ommended choice is 24-hr ambulatory measurement or repeated at-home measurementfollowing a well-defined protocol (JNC VII, National High Blood Pressure Ed-ucation Program Working Group, but none of the available quantitative reviewsprovides separate results for ambulatory versus office measures of BP because almost allstudies used office measures only. Office measures are unreliable, as they are prone toinclude white-coat hypertensives (i.e., those individuals who react with a large BP increaseto the measurement situation itself). Also, if only office measures are taken, habituationcan occur and measurement habituation can be mistaken as a treatment effect (Liu et al.,Selenta, Hogan, & Linden, Given that office BPs may confound with measure-ment reactivity and habituation, length of baseline will affect the measured BP differencesthat represent pre- and post-treatment BP levels. Jacob et al. and Eisenberg et al.
observed that studies with longer baselines usually started with lower BPs that were The Efficacy of Behavioral Treatments for Hypertension
attributed to measurement habituation effects, and that studies with low initial BP levelslead to much smaller treatment responses. The larger treatment effects seen in studies withhigh initial office BP readings and short baselines, may then masquerade as a treatmenteffect.
Probably the most promising avenue for researchers to avoid the reliability and validity problems of office measures is via the use of ambulatory BP measurement (ABPM) devices,which obtain 24-hr BP averages in the natural environment. The advantages of ABPMare: (a) Much improved test–retest stability given the increased number of measures andwider sampling, and (b) a greater potential for differentiating true hypertensives frommeasurement-reactive patients (“white-coat” responders; Pickering et al., Giventhat white-coat responders do not habituate to repeated measurement, they also cannotbe detected if only office measures are used (Selenta et al., Furthermore, ABPM ismore clinically meaningful in that 24-hr averaged ambulatory pressures are better long-termpredictors of the development of hypertension than lab resting measures (Perloff, Sokolow,& Cowan, Perloff, Sokolow, Cowan, & Juster, and averaged ambulatoryBPs also relate more closely to target-organ damage and mortality outcomes than dolab measures (Parati, Pomidossi, Albini, Malaspina, & Mancia, The disadvantagesof ABPM are well known, namely higher equipment cost and a more cumbersome anddemanding protocol that requires additional motivation and time of the patient and researchstaff.
A second, even more critical feature for the observable differences in outcome, is the degree of BP elevation at the beginning of treatment. Linden and Chambers confirmed Jacob et al.’s observation that initial BP levels strongly influence the magni-tude of observed treatment effects irrespective of what treatment is given. Drug therapieswere initiated at significantly higher initial levels of BP than non-drug therapies, withaverage pressures of 154.1 versus 145.4 mmHg SBP and 101.5 versus 94.3 mmHg DBPfor drug/non-drug treatments, respectively. Given that the regression coefficients for BPchange as a function of initial BP level are already known, it was possible to make math-ematical adjustments to observed treatment effects. After such adjustment for differencesin initial BP levels, the effect sizes for non-drug therapies increased from d = −1.19 tod = −1.71 for SBP, and from d = −1.13 to d = −1.92 for DBP. These effect sizes ofindividualized psychological therapy matched the effect sizes of drug treatments for SBPand DBP reduction (Linden & Chambers, These findings suggest that some non-drug therapies may be quite effective, especially when these differences in pre-treatmentBP levels are taken into account. This effect of a powerful impact of pre-treatment BP levelon subsequent BP reduction is highly consistent across studies (see Table indicatingthat 40% of the variance in BP reductions after treatment is accounted for by initial BPlevel and is unrelated to treatment type.
Table II.
Correlations Between Pre-Treatment BP Levels and Subsequent Treatment-Induced BP Changes Linden and Moseley
Given prevailing beliefs about the limited efficacy of psychological treatments for hypertension (JNC VII, it is typically difficult to recruit patients with truly highBPs into non-drug studies, especially when researchers are trying to recruit via physicianreferral.
We are aware of only one study that systematically used high entry BP and ambulatory BP monitoring (Linden et al., While a single study cannot absolutely settle any claimfor effectiveness, this study nevertheless illustrates the possibly different conclusions thatwould be drawn from office versus ambulatory BP studies and low versus high initial BPstudies. Consistent with conclusions and recommendations from previous reviews, thisclinical trial used conservative measurement strategies (e.g., ABPM as a screening tool andas study endpoint), high initial BPs, and individualized, one-on-one treatments. Men andwomen aged 28–75 years, with mean ambulatory BP greater than 140/90 mmHg, received10 hr of individualized stress management training using semi-standardized treatmentcomponents. Patients were randomly assigned to either immediate treatment (n = 27) ora wait-list control group (n = 33). Participants on the wait-list were subsequently offeredtreatment. Six months follow-up data were available from 36 of the 45 participants whocompleted the treatment. Measures were 24-hr mean ambulatory BP, lipid levels, weight,and psychological measures. Treatment led to a significant reduction in BP, whereas BPremained unchanged in control subjects (−6.1 versus 0.9 mmHg for SBP, and −4.3 versus0.0 mmHg for DBP from pre-test to the end of treatment). When the wait-list control groupwas later treated, BP was similarly reduced by −7.8 (SBP) and by −5.2 (DBP) mmHg.
For the combined sample, total change at 6-month follow-up, as measured by ABPM, was−10.8 and −8.5 mmHg for SBP and DBP, respectively, reflecting ESs of d = 1.13 andd = 1.24. The level of BP at the beginning of treatment was highly correlated with BPchange (r’s = .45 and .51 for SBP and DBP, respectively). The amount of SBP changewas positively correlated with reduction in psychological stress (r = 0.34) and change inanger coping styles (r’s ranging from .35 to .41). A striking finding in this study was thatBP had been assessed via office and ambulatory readings (Linden et al., and whilethe individualized treatment led to clinically meaningful changes in 24-hr ambulatorymeans, it revealed no corresponding change in office measures. In the wait-list controlgroup, both office and ambulatory BP remained equally unchanged. At a minimum, thesedifferential results suggest that one cannot safely generalize from treatment-induced officeBP readings to the more ecologically valid ambulatory readings. This observation placesstringent limits on the interpretability of the absolute changes observed in the great majorityof psychological interventions.
CONCLUSIONS AND RECOMMENDATIONS
Very much contrary to the conclusions drawn by early consensus committees (JNC VII, The Joint National Committee on Detection, Evaluation, and Treatment of HighBlood Pressure, there appears to be a rich body of randomized controlled trials ofpsychological treatments for hypertension that permits a variety of clinically relevant con-clusions. When all studies are aggregated and quantitatively reviewed without considerationfor critical protocol differences, the behavioral treatments produce moderately reliable ef-fects, in the neighborhood of 6–10 mmHg BP reduction for pre–post comparisons (Linden& Chambers, Slightly lower values are observed when psychological interventions The Efficacy of Behavioral Treatments for Hypertension
are compared to wait-list or other minimal attention controls. Effects appear to be signifi-cantly larger (reduction of 7–15 mmHg; Linden & Chambers, when individualizedor multi-component approaches are offered. The most effective psychological treatmentsproduce the same level of SBP reductions as do typically used antihypertensive drugs;with respect to DBP changes, however, drug effects are notably stronger (which is at leastin part attributable to the fact that the drug treatment trials were initiated at higher BPlevels; Linden & Chambers, To create additional context for the interpretation ofthese results, the reported absolute BP reductions for drug treatments averaged −16/ −11(SBP/DBP) mmHg; for other non-drug approaches, the numbers were −11/ −8 mmHg forweight-reduction programs, −13/ −9 mmHg for exercise programs, and −16/ −8 mmHgfor sodium restriction approaches (Linden & Chambers, In addition to attesting to the efficacy of behavioral treatments for hypertension, the available results can also be considered a consensus opinion if related to the guidelines thatwere created by the Association for Applied Psychophysiology and Biofeedback (LaVaqueet al., and that are also used by medical consensus committees (Concato, Shah,& Horwitz, Our review process itself was guided by these review principles. Assuch, hypertension is a clearly defined disease endpoint that can be reliably measured andconfounds are well known (i.e., age, medication status, race).
The guidelines urge that classifications of claims about the usefulness of interventions should be linked to a five-step hierarchy, where Level 5 represents the strongest evidence. Bydefinition, the existence of a single meta-analysis on therapy outcome implies that multiplerandomized controlled trials have been conducted, and the presence of replicated, significanttreatment effects (relative to a wait-list control condition) reflects Level 4 evidence. Ourfindings indicate that behavioral/psychophysiological interventions typically are superiorto sham or wait-list treatments, thus unequivocally representing Level 4 evidence.
A requirement for double-blind studies cannot reasonably be adopted for psychological interventions; both patients and therapists will know that they are actively engaged intreatment. An exception to this claim is the possibility of offering sham treatments, whichin pure biofeedback studies can consist of non-contingent biofeedback signals. The Nakaoet al. review of biofeedback interventions indeed reveals that sham treatments leadto lesser BP reductions than active treatments, while sham treatments themselves were notinert. Claims about the presence of Level 5 evidence are equivocal for this review, as theyrequire an investigational treatment to be superior to a sham treatment (true for biofeedbackstudies, Nakao et al., and/or superior to drug or other bona fide treatments. The latteris not true of biofeedback because biofeedback is not superior to drug treatments. Level5 evidence (LaVaque et al., requires that, in at least two studies, credible shamtreatments have been shown to be superior to no treatment, and that the experimentaltreatment is additionally superior to the sham treatment outcome. The review by Nakaoet al. indicates that this level of evidence is available for some biofeedback treatmentsbut only when compared to other bona fide biofeedback treatments. This conclusion cannotbe extended to the comparison of biofeedback with drugs that produce larger effects,nor is there Level 5 evidence that biofeedback outcomes are superior to other bona fidepsychological treatments. Note that all of these conclusions require that one accepts officeBP readings as clinically useful.
The findings presented in Table clearly show that psychological interventions are efficacious with typically modest-to-large effects sizes. Comparison of psychological treat-ments with drug treatments can serve as a test of clinical utility because pharmacological Linden and Moseley
agents are considered the gold standard and have been shown to reduce morbidity and mor-tality (JNC-VII, The most sophisticated psychophysiological treatments, in turn,when initiated at the same level of BP as drug treatments, are likely to lead to the sameclinical benefits (Linden & Chambers, However, this has not yet been subjected to adirect trial, and the true long-term effects of psychological treatments for hypertension areunknown. Hence, there continues to be a void of knowledge regarding long-term clinicalutility of psychophysiological interventions. To summarize, psychological treatments meetLevel 4 Evidence of Efficacy (for ambulatory and office BP).
A randomized assignment comparison of a purely psychological treatment with a fre- quently prescribed, known-to-be-effective drug is urgently needed. Although not directlycomparable, Kostis et al.’s work is illustrative in this respect. Patients with estab-lished hypertension were randomized to receive either a multi-component non-drug package(relaxation, exercise, and nutrition counseling) or were given a standard, therapeutic doseof a known, effective antihypertensive medication (i.e., propranolol). Both treatment con-ditions were associated with equally large and clinically meaningful BP reductions, andthe non-drug approach led to additional desirable reductions in body weight (whereas thedrugs did not).
The results from the Linden et al. study, which utilized ambulatory BP endpoints and at least moderately high BP entry levels, also reaffirm that high initial BP levels arestrongly predictive of large changes following treatment. In turn, this principle also appliesto the typical pharmacological trial for hypertension (Linden & Chambers, Therefore,any fair comparison of various treatments for hypertension requires that all treatments startat the same BP levels. Such a requirement for pre-treatment equivalence has traditionallynot been met when non-drug treatments have been tested, which leads to a co-incidentalbut rather critical underestimation of possible observable effects. There is a high likelihoodthat the Linden et al. study was more successful than previous studies because (1)white-coat hypertensives had been screened out by use of the elevated 24-hr BP inclusioncriterion, and (2) the measurement habituation confound noted by Eisenberg et al. had been avoided.
Although speculative, the study of change in the psychological variables provided some clues as to the relationship between psychological and biological aspects of hypertension.
At the biological level, reviewers routinely report a very high inter-correlation betweenSBP and DBP changes (in Linden et al., these correlation were r = .91); when onechanges so does the other, and in the same direction. The relatively largest BP changeswere seen in those patients who showed stress reduction and more adaptive anger copingstyles. This is also consistent with other studies showing a link between BP levels and thesesame psychological variables (Davidson, MacGregor, Stuhr, & Gidron, It appearsthat successful stress reduction and changes in anger coping habits are the most promisingtargets for psychotherapy aimed at reducing BP. It is also noteworthy that different typesof biofeedback have distinct effects on BP, with the seemingly most obvious biofeedbacktarget, namely BP itself, being the least effective approach.
The emphasis of this review paper has been on the immediate BP response of hyperten- sives to psychological treatment although there is no doubt that the most critical questionsrelate to (a) long-term effects of such interventions, (b) ability to prevent the developmentor worsening of heart disease, and (c) ultimate reduction of cardiovascular mortality. Thevarious review papers have paid little attention to the stability of benefits, and this is largely The Efficacy of Behavioral Treatments for Hypertension
due to the relative neglect of follow-ups in the controlled trials. Existing data provide anambiguous picture: Kaufmann et al. provided extensive follow-up information ofup to 1-year that suggested that obtained BP benefits are maintained up to 9 months butthen disappear at 12 months. Linden et al. conducted a 6-month follow-up andreported continuing reduction in BP at follow-up above and beyond the benefits seen atpost-treatment. While there is general agreement that antihypertensive medications need tobe taken continuously for maintained benefits, there is an implicit hope with psychologicalinterventions that one bout of treatment will lead to lasting changes because patients arenow presumed to be equipped with self-regulation skills. However, this hidden expectationhas not been tested beyond the 12-month mark and, if anything (see Kaufmann et al.,may not materialize. Repeated treatments or booster sessions may help. There isno properly conducted study to date to assess psychological treatment effects on mortality,although a study of meditation with quasi controls suggested an improved 3-year survivalfor meditation and mindfulness practitioners (Alexander, Chandler, Langer, Newman, &Davies, Lastly, some patients may not expect BP reductions with psychologicaltreatments but would be happy if they could reduce or eliminate the need to take medi-cation. We know of one such study (Shapiro, Hui, Oakley, Pasic, & Jamner, wherea cognitive–behavioral treatment package yielded complete elimination of medication in55% of the sample, compared to only 30% elimination in the control group.
CLINICAL PRACTICE GUIDELINES
We posit that this review provides convincing evidence for the relative superiority of some psychological treatment approaches over others; this claim for differential resultsof various treatments also applies within the somewhat more homogeneous literature onbiofeedback interventions. The most effective interventions are individualized approaches,multi-component approaches, and temperature and electrodermal biofeedback. However,there is limited knowledge about the absolute changes that can be expected from psycho-logical treatments when measurement habituation problems and floor effect problems areeliminated. In this respect, there remains a critical void in the literature and more trials withstrong protocols and lengthy follow-ups are needed. Studies are also urgently needed thatcompare individualized with standardized treatments, provided that in both cases patientsstart out with equally high BP levels. Similarly, researchers need to tackle the question ofwhether careful pre-treatment screening of psychological predispositions can lead to differ-ential outcomes when a variety of psychological treatment options are carefully matchedto the specific presenting problems. For example, a patient with high anxiety levels wouldreceive a different treatment than a patient with a great deal of suppressed anger.
An important consideration for actual practice is that patients cannot just be assigned to a psychological treatment; patients themselves need to agree to participate in psychologicaltreatment, and some of them may prefer to take medication. Nevertheless, if patientswere provided with promising and clear information about the benefits of psychologicaltreatments, more of them might consider drugs to be only a second choice. Also, resultsfrom clinical trials are to some degree suspect in that patients who are willing to acceptpsychological therapies for hypertension are not necessarily representative of the entirehypertensive population; these patients may be particularly open to the concept of self-care.
Linden and Moseley
With respect to clinical practice guidelines, the available data help to decide on choice of technique, measurement tools, and endpoints. Additional recommendations are possiblebut are mostly based on clinical experience and are not backed by unequivocal researchfindings. We suggest that psychological therapies, as first-line or additional treatment ap-proaches for hypertensives, may be indicated when one or more of the following conditionsapply: 1. Medication side effects are severe.
2. Life-style changes (weight loss, exercise uptake) alone are not enough to lower the BP to the normotensive range, and/or the patient needs psychological support toimplement and maintain these changes.
3. The patient himself/herself prefers non-drug treatment, has a specific interest in the self-regulation of physiological function, and has realistic expectations.
4. The patient has a family history of hypertension and cardiovascular disease and wishes a preventive measure even if his/her BP is not sufficiently elevated to warrantdrug treatment.
5. The patient has a stressful life-style and has noticed a slow increase in BP over time, or sees a great deal of variability in BPs as a function of daily stress exposure.
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