Medical Hypotheses 1

I Mdd Jfpkla ~~~uKLld1991

(1991) 36, s-59

Evaluating Primary Practice: Proposals for a Modified Model Suited to Chiropractic Care J. R. JAMISON Department of Diagnostic Sciences, Phi/lip Institute of Technology, Plenty Road, Bundoora, Vitoria, Australia 3093

Abstract - Although chiropractic care is not yet considered to have achieved scientific validity, it enjoys widespread public acceptance. It is hypothesised that one of the barriers to chiropractic establishing scientific validity is the propensity of researchers to frame their randomized controlled clinical trials according to a biomedical rather than a biopsychosocial model. It is proposed that while chiropractic care should be required to establish a cause-effect relationship between spinal manipulation and clinical response, subjective patient-valued outcomes should also be monitored. For chiropractic care to be adequately assessed recognition needs to be given to the usefulness of qualitative measurements in health care. Interventions selected solely upon the basis of statistical significance run the risk of overlooking clinically meaningful outcomes.

Introduction

problems confirmed that chiropractic intervention is According to the NHANES II survey, between at least as effective as that offered by the medical 1976-80 US subjects with low back pain were found profession (8). In view of persistent public acceptance and leto predominantly seek assistance from general pramgal recognition by registration boards of chiropractic titioners (59%). orthopaedic surgeons (37%) and chipractice (9), it is desirable that chiropractic care be ropractors (31%) (1). It has further-more, somewhat validated according to the standards conventionally controversially been suggested thar ‘Although, it is employed within the health care system. It is, howobvious that the most appropriate person to manage spinal dysfunction is the physician, it is even more ever, hypothesised that neither the biomedical model painfully obvious that the medical profession alone nor conventional use of randomized controlled clinicannot meet the existent health care demands of this cal trials provides an adequate framework for evaludysfunction’ (2). Despite traditional medical opposi- ating the clinical efficacy of chiropractic care. tion to chiropractic (3, 4), the public appears convinced of the helpfulness of chiropractic care in the The biomedical model: disease orientated health care management of back pain (5, 6,7). An independent retrospective study of patient satisfaction and per- Chiropractors function at the consumer-health care ception of functional improvement of neck or back system interface. The inadequacy of the biomedical Dare received 17 December 1990 Date accepted 28 February 1991

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54 model as a framework for evaluation of chiropractic care becomes apparent when one considers that primary practice must encompass most of the patient’s iirst contact problems (10). The consumer-health care system interface is not confined to a consideration of disease, it also takes cognisance of wellness. Adequate health care at the primary contact level consequently rests upon the more comprehensive World Health Organization’s perspective of health as physical, psychological and social wellbeing. This perspective seeks accommodation in the interstices between wellness paradigm of alternative health care and the disease paradigm of medicine. Evaluation of such clinical intervention is inadequately formulated within the conceptual framework of the biomedical model and the research corollary of a randomized clinical trial; it is better accommodated by Engel’s ‘biopsychosocial’ (11) or Howie’s ‘bchavioural’ model (12). A biopsychosocial model, while adherent to a cause-effect philosophy does allow for consideration of behavioural variables, Such a model could permit recognition of lifestyle both as a cause of disease and as a consequence of influences such as social stress, personality and inadequate social support (13); it could also acknowledge that the clinical presentation of a condition and responses to intervention are subject to psychosocial influences. Only so comprehensive a model can furthermore hope to simultaneously accommodate consideration of disease, an organic state; illness, an individual’s psychophysiological or personal perception of not feeling well; and sickness, a social phenomenon (14). A paradigm which has evolved beyond the confines of the Cartesian reductionist model and evolved to take cognisance of a more holistic world view is need& at the consumer-health care system interface. At the service level, the shift from a biomedical model to a biopsychosocial model implies a tranformation from high cost, impersonal, technologically advanced and materialistically orientated intervention to a more low cost, community accessible form of self-care which values quality-of-life outcomes (15). At the research level, a parallel adjustment is the recording of tberapeutic outcomes which range from objective changes in disease status through subjective patient perceptions to patient valued health changes. A research model suited to primary practice takes cognisance of wellness; it recognises that health status is as much a matter of functional capacity as is the absence of structural/organic aberration. A research model is required which measures hitherto ignored outcomes - including subjective perceptions of wellbeing and

MEDICAL HvPcnXEsEs marginal improvements in some people. Bandomized controlled clinical trials, formulated within the framework of the biomedical model, provide a reliable means of objectively determining probable outcomes following specified therapeutic interventions. Although acknowledging that predictability is intimately linked with the methodology of clinical trials, the biopsychosocial model appreciates that wellness, despite its inherent subjectivity, is a valid outcome measure. Ahhough current research tends to suggest that manipulation appears to be at least equivalent, if not superior, to other conservative measures (16), manipulation, including chiropractic manipulation, has failed to establish a satisfactory scientific track record within the conventionally accepted biomedical/clinical trial framework. Bloch, in an analysis of the methodology used in clinical back pain trials, found that of 147 reports in an indexed medical journal only 2 were valid randomized and 4 properly controlled cohort studies (17). In his review, BNIWS~~ described similar methodological constraints upon the interpretation of data derived from clinical trials of spinal manipulation (18). Methodological problems encountered when evaluating manipulation using conventionally accepted research methodology are compounded by conceptual incompatibility between a reductionist evaluation of organic and a holistic assessment of functional disorders. Despite the paucity of scientifically valid evidence justifying the clinical efficacy of chiropractic manipulation, ‘Subjective improvement in patients under chiropractic care has undoubtedly been witnessed by thousands of chiropmctors and millions of patients* (19). The discrepancies emerging between objective scientific research and clinical practice experience may be attributable, at least in part, to some contradictions between science and clinical practice. Science and clinicalpractice are non-identical activities In seeking to explain how manipulation can enjoy clinical success in the absence of scientific validity, it is well to remember that science and clinical practice are non-identical activities. ‘Scientitic norms concern knowledge and do not deal directly with practical outcomes; risk is not a central concern. In contrast the goal of practice is healing; it is particular and local in its nature..Practice consists of encounters that require action, sometimes conclusive action; the avoidance of harm is a key norm’ (20). The priorities of clinical practice arc distinct from those of medical science.

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EVALUNTNG PRIMARY PRACllCEz CHlROPRACl’IC CARE

Manipulation is a relatively safe mode of intervention. The most serious complications of manipulation are likely to arise from cervical manipulation, yet a survey of members of the Swiss Society for Manual Medicine reported slight neurological complications in one out of 40 000 and important complications in one out of 400 000 cases (21); a literature search over a 50-year period disclosed 107 manipulation accidents (22); it has been extimated that over a lfi-year period some 5 million manipulations given at the National College of Chiropractic have not resulted in any manipulation-induced vettebrobasilar artery accidents (23); and 2-3 serious incidents involving the vertebrobasilar system are estimated to occur in 1 million manipulations to the upper cervical spine (24). Even a medical writer cautioning his colleagues about the dangers of chiropractic treatment, although claiming the literature contained numerous reports of patients worsened by this intervention, only quoted eight papers published between 1947 and 1985 (25). Active intervention which is perceived as safe may be readily accepted by the consumer. Since the safety of manipulation does not appear to be a major issue, it is the efficacy of this form of therapy which deserves critical scrutiny. Outcomes selected to represent appropriate criteria for evaluating efficacy become critical research variables. Under circumstances in which efficacy is unproven, the cost:benefit ratio of an intervention may approximate infinity. Even though manipulation is not the only clinically implemented intervention lacking adequate scientific justification Q&29), it is important that such validation be actively sought. Consistency with the clinical practice norm of safe active intervention does not obviate the need for clinical efficacy. The framework within which manipulation in general and chiropractic in particular should be evaluated does however require fresh scrutiny. From plants to people The natural science model derived from the agricultural-botany paradigm provides the cognitive framework underlying the methodology of randomized clinical trials. If the agricultural-botany paradigm is inappopriate for evaluating clinical outcomes, then the randomized clinical trial is not necessarily the optimal research tool for health care. Inappropriately applied randomized clinical trials may provide results which achieve a veneer of scientific respectability but contribute little to existing knowledge (30). Although chiropractic should justify its spinal manipulative therapy taking cognisance of a biomedical framework which seeks to identify natural remissions and cyclic disorders, it may not be desirable

for chiropractic to extricate the psychosocial aspects of its clinical success. It may therefore be necessat-y for chiropractic to seek clinical validation taking cognisance of the clash between the biomedical and biopsychosocial models of health care, between the agricultural-botany and social-anthropological research paradigms. Valid measures of wellbeing Valid measures for evaluating clinical interventions within the biopsychosocial model include awareness of subjective outcomes - even the placebo effect. The placebo effect, an inevitable component of all personalized clinical intervention, need not constitute a clinical research dilemma (31). In fact, ‘The trivialization and rejection of placebo effects, the intolerance for clinical design trials that do not “rule out” placebo effects, and the secondary importance given to outcome variables in which biomedical research have created a climate in which the prime directive in clinical research, the promotion of human health, is often lost’ (32). The effectiveness of the chiropractic clinical encounter involve all the psychosocial elements of ‘acceptance/validation, expectation/explanation, the instrumental factor or clinical action and personal engagement’ (33). Chiropractic acceptance of the patient’s complaint and validation of his/her condition, the practitioner’s charismatic belief that this patient can be helped, the person+rientated time spent laying on of hands and provision of a believable explanation of the patient’s malady may all be constru& as placebo effects, but are an integral component of chiropractic practice and patient wellness perception. A double blind study of the efficiency of chiropractic spinal adjustment considered that non-manual control treatments presented a problem in research design ‘as the placebo effect of laying on of hands is not adequately compensated for’ (34). Validation of chiropractic according to an appropriate scientific methodology evolving out of a biopsychosocial model of health care may not demand neutralization of the placebo effect. Once the placebo effect is acknowledged as a help ful therapeutic phenomenon in clinical research, patient satisfaction becomes a valid outcome measure (35). Attempts to objectively measure psychosocial functions in patients with low back pain have been reported (36, 37). Recent studies recommend that clinicians pay close attention to the qualitative aspects of their patient’s behaviour during clinical assessment (38). The patients’ understanding of their condition is potentially an important variable impacting upon the prognosis of low back pain cases (39). A

56 medical trial of manipulation for chronic neck pain found no significant difference between manipulation and control groups; 21 patients received diazepam and manipulation, 18 patients served as control and also received diazepam (40). Patient outcome statements and visual analog scales for pain did however favour manipulation. A controlled trial of the cervical manipulation of migraine found no significant difference between placebo, chiropractic, medical practitioner or physiotherapist manipulation in reducing the frequency, duration or induced disability of migraine attacks; chiropractic patients reported a greater reduction in pain associated with their attacks (41). Patient perceived outcomes are respected in a wellness orientated research model. Patient opinion is a component of successful clinical intervention at the primary level of health care. The preferred relationship model of patient-practitioner interaction at the primary level of health care (42) is well demonstrated by the humanized approach used by chiropractors in clinical practice. It is today widely accepted that the most productive interchange between consumer and provider at the primary contact level of health care is likely to be achieved within a mutual participation or guidance-cooperation format. Chiropmctols have embraced, indeed some may claim pioneered, a holistic philosophy of health care (43). ‘The uniqueness of chiropractic is really not so much in its clinical methodologies per se whether it be adjustments, manipulation or physiological therapeutics -but rather by its wholistic concerns for the total internal/external environment of the patient...’ (44). This noneducationist, person orientated form of health care is consistent with contemporary trends in health care and the emergence of the wellness paradigm. This personalized approach also impacts on physical aspects of research design. The favoured agricultural-botany research paradigm of the biomedical model does not allow for individual variability - it seeks to compare equals under equivalent circumstances with the test intervention being the only variable. Chiropractic manipulation takes cognisance of the physical uniqueness of individuals. A major problem with clinical trials evaluating the efficacy of manipulation is that they use a standardized manipulation technique; in chiropractic practice the nuances of the intervention are modified according to the needs of the presenting patient. Controlled randomized clinical trials therefore fail to assess manipulation as it is practised clinically (45). Another aspect of the chiropractic model of care, consistent with primary practice experience but poorly accommodated within the biomedical model,

MEDKAL HYFoTHEsEs is an emphasis on functional change. At least one study of general medical practice finds that half of primary medical care encounters are with persons devoid of detectable organic pathology; the pathology present in the remaining clinical encounters is self-limiting in 7 out of 10 cases (42)! Spinal disorders conform to this pattern. It has moreover been submitted that the pathology model serves as a poor predictor of back pain (46). A functional model of back pain has implications both for diagnosis and therapy. The relationship between the mobile segments of the spine ‘leads to a more functional than anatomical approach to pathology...* manipulators observe, feel, and describe spinal lesion such as subluxation and vertebral fixation and blockage’ when no pathological lesion can be identified (47). Studies documenting the benefits of functional rehabilitation and the failure of commonly prescribed general medical practice interventions in the treatment of low back pain to achieve a beneficial effect (48,49) all support the chiropractor’s proposition that a proportion of back problems are functional rather than pathological disorders. Papers are emerging in the medical literature which advocate early mobilization rather than rest (50, 51). In advocating a new model for the treatment of low back pain Waddell suggests that therapy should be aimed at limiting functional disability rather than treating illness (52). Although a team approach to spinal care appears to offer health care advantages (53-56), in the absence of consensus regarding diagnostic criteria for the recognition of spinal conditions, no realistic investigation of chiropractic efficacy is possible. In addition to cognitive limitations imposed by a pathological model and/or failure to adequately define wellness outcome measures potentially hindering recognition of the benefits of chiropractic care, the level of statistical significance chosen and/or the number of subjects included in a trial may actively discriminate against therapies which offer a marginal benefit to some. If the probability of a type II (false negative) error is high, then the study may lack the power to demonstrate that a treatment offers a real benefit. 71 ‘negative’ randomized trials reported during 1960-77 in 20 reputable medical journals, such as J_ancet and JAMA, were analysed (58). 67 of the trials had a greater than 10% risk of missing a true 25% therapeutic improvement; with the same risk, 50 of the trials could have missed a 50% improvement. In many cases the sample size used in the trial was too small to offer a reasonable chance of detecting a clinically meaningful benefit. Many therapies discarded as ineffective after statistically inconclusive or negative trials may be clinically meaningful. In a

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EVALUATING PRIMARY PRACl-ICEz CHIROPRACTIC CARE

review of the Australian medical literature between 1976 and 1978, some 191 papers of the 1416 reviewed reported negative results (59). Of these, 72 had sufficient evidence to estimate the probability of type II errors. 43 of these admissable studies had a greater than 50% chance of missing a true 10% difference. To ensure that trials achieve clinically meaningful results and adhere to the conventions of scientific clinical research, larger study populations are often required. For example, within the limits commonly used in clinical trials, 1282 patients are required to demonstrate a 10% improvement under a particular therapy; 190 patients are required to demonstrate a 25% improvement. This assumes a study with a 5% risk of a type I (false positive) error, a 5% risk of a type II (false negative) error and a response rate in the control group of 50%. It is not unusual for 50% of patients receiving placebo intervention to report some improvement. Put succinctly, ‘Although the approximation is crude, it appears that about 100 subjects per treatment group are sufficient if 70% power is acceptable’ (60). At this level there is a 30% chance of missing a biologically real response to therapy. It would therefore appear that when evaluating therapies for low back pain...‘a very minimum of 100 pairs...is needed in order to achieve statistical confirmation of trends showing differences between treatment groups’ (61). Most published medical trials of manipulation have too few study subjects upon which to base definitive therapeutic conclusions. The Godfrey et al study which is critical of manipulation may be characterized as such a study (62). Of the 200 referred patients only 109 were included in the study and 81 constituted the final study group. The minimum number of subjects needed in a study comparing 4 groups is 400 - provided, of course, a 30% chance of missing benefit is considered a fair trial! Similar criticisms can be made about the validity of the Parker et al initial and follow-up studies (41,63). In the Parker study, although migraine symptoms were significantly reduced in all three treatment groups no significant difference in outcome was found between the groups receiving mobilization, chiropractic manipulation or manipulation from physiotherapists or medical practitioners. The total study size was 85 (82 after drop-outs) patients. The adoption by the Parker trial of the stringent alpha 0.01 level of significance further increases the likelihood of type II error. Within the framework of these clinical trials it is unlikely that any marginal benefits attributable to manipulation in general and/or chiropractic manipulation in particular would be detected. The marginal benefits appreciated by patients in a functional wellness model are not

detected given the conventional standards of clinical trials. Any research model which respects wellness needs to take cognisance of patient valued outcomes. This includes monitoring interim benefits perceived by the patient. Unwarranted rejection of manipulation may also result from the biomedical model undervaluing short-term benefits. Although manipulation does not appear to significantly modify the recurrent nature of backache, it does appear to offer some benefit in the short-term management of acute back pain (64, 65). In fact, although nearly all of 59 reported trials of therapy for low back pain are poorly designed and therefore prove nothing, the only therapy shown by properly designed trials to have immediate and/or short-term benefit is manipulation (66). Such shortterm benefits can have immense psychosocial impact, Manipulation may enable a more rapid return to work and reduce the potential for compensation neurosis and other psycholog!cal problems. Not only is it possible that clinically meaningful outcomes are being statistically rejected, it is also possible that the benefits of psychosocially significant outcomes are being under-estimated. Curative intervention is mom highly valued than palliative therapy, nonethless the tempo rary alleviation of pain is a substantial contribution to personal wellbeing. Failure to change the natural history of disease conventionally emphasised within the biomedical research paradigm may not necessarily result in a meaningless clinical outcome when wellness, function and the patient’s perspective are regarded as valid componenets of health care. Towards a relevant evaluation model

Because care at the consumer-health care system interface is at least as much concerned with wellness as disease, health is best served within the framework of a biopsychosocial rather than biomedical model. Chiropractic with its holistic approach is consistent with this perspective of primary contact practice. Evaluation of chiropractic care should conseqxmly occur within a methodological framework imposed by the biopsychosocial rather than the biomedical model. Modification of the conventional use of randomized controlled clinical trials is therefore proposed for the evaluation of chiropractic practice. In the rush towards a holistic personalized wellness orientated model of clinical practice it is, however, important that the advantages derived from a biomedical perspective and randomized clinical trial methodology be retained. The randomized clinical trial remains the best available method for determin-

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MEDICAL HYPOTHESES

ing the natural history of a disease, for comparing therapeutic strategies and for evaluating the effect of manipulation. It can, however, become a more realistic measure of clinical efficacy when wellness outcomes are also considered Any new research framework for evaluating the efficacy of chiropractic care within the biopsychosocial model of health care requires that: -

functional tests, like structural and biochemical changes, are recognized as helpful diagnostic criteria in patient assessment; palliative or interim improvements valued by patients are accepted as meaningful outcome measures; subjective improvements are regarded as valid wellness indicators.

Modification of randomized clinical trials requires a change from a narrow quantitative research focus to a broader qualitative perspective. Instead of conclusions being almost exclusively based upon statistical significance, definitive management decisions should be derived from research which takes cognisance of the importance of substantive wellness gains. Data collection and interpretation within a biopsychosocial research model may differ from that based upon a biomedical model. In the disease model interventions which alter the natural history of disease are valued, in the weltness model all health gains arc documented. Short-term functional gains, hitherto valued by the patient but ignored by scientifically objective investigation, are now recognised as having a potentially important impact on psychological and socioeconomic wellbeing. In proposing a new model for evaluating the efficacy of chiropractic practice, it is suggested that the type of outcome measured be modified, not that the necessity for demonstrating a cause-effect relationship be abandoned.

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