Development of Acute Myocardial Infarction Mortality and Readmission Models for Public Reporting on Hospital Performance in Canada.

BACKGROUND: Given changes in the care and outcomes of acute myocardial infarction (AMI) patients over the past several decades, we sought to develop prediction models that could be used to generate accurate risk-adjusted mortality and readmission outcomes for hospitals in current practice across Canada. METHODS: A Canadian national expert panel was convened to define appropriate AMI patients for reporting and develop prediction models. Preliminary candidate variable evaluation was conducted using Ontario patients hospitalized with a most responsible diagnosis of AMI from April 1, 2015 to March 31, 2018. National data from the Canadian Institute for Health Information was used to develop AMI prediction models. The main outcomes were 30-day all-cause in-hospital mortality and 30-day urgent all-cause readmission. Discrimination of these models (measured by c-statistics) was compared with that of existing Canadian Institute for Health Information models in the same study cohort. RESULTS: The AMI mortality model was assessed in 54,240 Ontario AMI patients and 153,523 AMI patients across Canada. We observed a 30-day in-hospital mortality rate of 6.3%, and a 30-day all-cause urgent readmission rate of 10.7% in Canada. The final Canadian AMI mortality model included 12 variables and had a c-statistic of 0.834. For readmission, the model had 13 variables and a c-statistic of 0.679. Discrimination of the new AMI models had higher c-statistics compared with existing models (c-statistic 0.814 for mortality; 0.673 for readmission). CONCLUSIONS: In this national collaboration, we developed mortality and readmission models that are suitable for profiling performance of hospitals treating AMI patients in Canada.

CONTEXTE: Compte tenu des changements apportés au cours des dernières décennies aux soins des patients ayant subi un infarctus aigu du myocarde (IAM) et aux issues d'un tel événement, nous avons voulu élaborer des modèles prédictifs pouvant servir à calculer de façon précise les résultats relatifs à la mortalité et aux réadmissions, ajustés selon les risques, pour les hôpitaux dans la pratique actuelle au Canada. MÉTHODOLOGIE: Un groupe national d'experts canadiens a été mis sur pied et a reçu le mandat de définir les critères appropriés applicables aux patients ayant subi un IAM aux fins de déclaration des cas et d'élaborer des modèles prédictifs. L'évaluation préliminaire des variables proposées a été effectuée à partir de patients hospitalisés en Ontario entre le 1er avril 2015 et le 31 mars 2018 chez lesquels l'IAM était le diagnostic principal à l'origine de l'hospitalisation. Les données à l'échelle nationale de l'Institut canadien d'information sur la santé (ICIS) ont été utilisées pour élaborer des modèles prédictifs d'IAM. Les deux principales issues évaluées étaient la mortalité hospitalière toutes causes confondues à 30 jours et la réadmission urgente toutes causes confondues à 30 jours. Le pouvoir discriminant de ces modèles (mesuré par la statistique C) a été comparé à celui des modèles existants de l'ICIS dans la même cohorte de l'étude. RÉSULTATS: Le modèle de mortalité par IAM a été évalué auprès de patients ayant subi un IAM, dont 54 240 en Ontario et 153 523 dans l'ensemble du Canada. Nous avons observé un taux de mortalité hospitalière à 30 jours de 6,3 % et un taux de réadmission urgente à 30 jours toutes causes confondues de 10,7 % au Canada. Le modèle canadien final de prédiction de la mortalité par IAM était constitué de 12 variables et avait une statistique C de 0,834. Pour la réadmission, le modèle comportait 13 variables et présentait une statistique C de 0,679. Le pouvoir discriminant des nouveaux modèles d'IAM présentait une statistique C supérieure à celle des modèles existants (statistique C de 0,814 pour la mortalité et de 0,673 pour la réadmission). CONCLUSIONS: Dans le cadre de cette collaboration nationale, nous avons élaboré des modèles prédictifs de la mortalité et de la réadmission hospitalière qui permettent d'établir un profil des résultats obtenus par les hôpitaux traitant des patients ayant subi un IAM au Canada.

Factors associated with door-in to door-out delays among ST-segment elevation myocardial infarction (STEMI) patients transferred for primary percutaneous coronary intervention: a population-based cohort study in Ontario, Canada.

BACKGROUND: Compared to ST-segment elevation myocardial infarction (STEMI) patients who present at centres with catheterization facilities, those transferred for primary percutaneous coronary intervention (PCI) have substantially longer door-in to door-out (DIDO) times, where DIDO is defined as the time interval from arrival at a non-PCI hospital, to transfer to a PCI hospital. We aimed to identify potentially modifiable factors to improve DIDO times in Ontario, Canada and to assess the impact of DIDO times on 30-day mortality. METHODS: A population-based, retrospective cohort study of 966 STEMI patients transferred for primary PCI in Ontario in 2012 was conducted. Baseline factors were examined across timely DIDO status. Multivariate logistic regression was used to examine independent predictors of timely DIDO as well as the association between DIDO times and 30-day mortality. RESULTS: The median DIDO time was 55 min, with 20.1% of patients achieving the recommended DIDO benchmark of ≤30 min. Age (OR> 75 vs 18-55 0.30, 95% CI: 0.16-0.56), symptom-to-first medical contact (FMC) time (OR61-120mins vs < 60mins 0.60, 95% CI: 0.39-0.90; OR>120mins vs < 60mins 0.53, 95% CI:0.35-0.81) and emergency medical services transport with a pre-hospital electrocardiogram (ECG) (OREMS transport + ECG vs self-transport 2.63, 95% CI:1.59-4.35) were the strongest predictors of timely DIDO. Patients with timely ECG were more likely to have recommended DIDO times (33.0% vs 12.3%; P < 0.001). A significantly higher proportion of those who met the DIDO benchmark had timely FMC-to-balloon times (78.7% vs 27.4%; P < 0.001). Compared to patients with DIDO time ≤ 30 min, those with DIDO times > 90 min had significantly higher adjusted 30-day mortality rates (OR 2.82, 95% CI:1.10-7.19). CONCLUSIONS: While benchmark DIDO times were still rarely achieved in the province, we identified several potentially modifiable factors in the STEMI system that might be targeted to improve DIDO times. Our findings that patients who received a pre-hospital ECG were still being transferred to non-PCI capable centres suggest strategies addressing this gap may improve patient outcomes.

The Transcatheter Aortic Valve Implantation (TAVI) Quality Report: A Call to Arms for Improving Quality in Canada.

Transcatheter aortic valve implantation (TAVI) is a disruptive technology that has dramatically changed the way clinicians care for patients with aortic stenosis. In 15 short years, this technology has progressed from first-in-human to the standard of care for high-risk and inoperable patients with aortic stenosis. In 2016 the Canadian Cardiovascular Society published the first ever report of quality of care for TAVI in Canada. This report provided multiple insights into evaluating such care delivered to Canadians and the challenges that lie ahead. In this article, we summarize these challenges and encourage cardiologists to join the call to arms for improving quality of TAVI care in Canada.

Quality of Care for Percutaneous Coronary Intervention: Development of Canadian Cardiovascular Society Quality Indicators.

Currently there are more than 40 centres in Canada that perform more than 65,000 percutaneous coronary interventions (PCIs) in a year. Considering the high volume of procedures and number of operators, the potential for variation in processes of care is high, and might lead to variation in the quality of care. As part of its quality initiative, the Canadian Cardiovascular Society convened a working group to develop a set of PCI Quality Indicators (QIs) that would be relevant, scientifically acceptable, and feasible to measure and report. The working group was comprised of clinical experts from across Canada and members of provincial and federal organizations involved in promoting the quality of health care. Using the Canadian Cardiovascular Society "Best Practices for Developing Cardiovascular Quality Indicators" methodology, a total of 23 QIs were proposed. Subsequent ranking and discussion led to the selection of 8 QIs. The selection and ranking of QIs were on the basis of clinical importance and relevance, scientific acceptability, and feasibility of their operationalization at a national level. The data definitions and technical notes of the QIs were refined after feasibility testing and Web consultation. Feasibility testing indicated that standardization and enhancements of knowledge infrastructure are essential to provide the comprehensive patient data necessary to evaluate the quality of PCI across Canada.

Outcomes of Patients With ST-Elevation Myocardial Infarction Receiving and Not Receiving Reperfusion Therapy: The Importance of Examining All Patients.

BACKGROUND: Hospitals treating patients with ST-elevation myocardial infarction (STEMI) may show good results with reperfusion treatment (fibrinolysis or primary percutaneous coronary intervention [PPCI]), but a comprehensive evaluation should factor in outcomes of patients with STEMI who do not receive reperfusion. We compared outcomes of patients receiving and not receiving reperfusion within a complete system of STEMI care by hospital type: PPCI centres, fibrinolysis centres, centres that only transfer for PPCI, and centres providing a mix of fibrinolysis and PPCI transfer. METHODS: All patients presenting to 82 Quebec hospitals with characteristic symptoms, a final diagnosis of acute myocardial infarction, and core-laboratory confirmed STEMI over two 6-month periods were studied. RESULTS: Of the total 3731 patients with STEMI, 2918 (78.2%) received reperfusion treatment (81% PPCI, 19% fibrinolysis); 813 (21.8%) did not. For reperfusion-treated patients, 30-day mortality was 5.4% in PPCI centres, 5.4% in fibrinolysis centres, 6.9% in transfer PPCI centres, and 6.0% in mixed centres (P = 0.55). For untreated patients, 30-day mortality was 15.7% (PPCI centres), 16.1% (fibrinolysis centres), 21.8% (transfer PPCI), and 24.6% (mixed) (P = 0.08). Adjusted mortality odds ratios for all patients were 1.00 (PPCI centres), 1.50 (95% CI: 0.97-2.32; fibrinolysis centres), 1.30 (0.95-1.78; transfer PPCI centres), and 1.58 (1.09-2.29; mixed centres). PPCI was within recommended delays in 35.4%, 11.9%, and 1.2% of PPCI, transfer, and mixed centres, respectively. CONCLUSIONS: Mixed centres had the highest crude and adjusted all-patient 30-day STEMI mortality. Relatively good outcomes of reperfusion-treated patients, despite long treatment delays, can misrepresent overall performance if untreated patients are not examined.

Canadian Cardiovascular Society Quality Indicators for Heart Failure.

A working group was convened by the Canadian Cardiovascular Society (CCS) in 2010 to identify quality indicators (QIs) for heart failure (HF). Using the CCS "Best Practices for Developing Cardiovascular Quality Indicators" methodology, a total of 49 "long-list" QIs was identified and rated. Subsequent ranking and discussion led to the selection of an initial "short-list" of 6 QIs to evaluate quality care, including daily assessment of blood chemistry indicators, chest radiography, patient education, in-hospital use of angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers, assessment of left ventricular function, and 30-day hospital readmission. The short-list QIs were selected as being important for quality assurance and because the patient information, for the most part, can be captured during the inpatient setting, which would allow these QIs to be adopted more easily. These 6 QIs were subjected to a feasibility test that found that even within the inpatient setting, there is a significant gap between the existing knowledge infrastructure and the necessary information-tracking processes to measure QIs. Only 1 QI (30-day hospital readmission) can currently be measured comparatively across Canada, although the other 5 of 6 short-list QIs can be measured using other data collected by jurisdictions. Standardization and enhancements to knowledge infrastructure are essential to provide the comprehensive patient data necessary to evaluate the quality of HF care across Canada.

Quality of Care for Transcatheter Aortic Valve Implantation: Development of Canadian Cardiovascular Society Quality Indicators.

Transcatheter aortic valve implantation (TAVI) is a relatively new procedure to treat aortic stenosis in patients at high surgical risk, and it is becoming increasingly available in Canada. Variation exists in the clinical care, program coordination, evaluation, and funding across provinces and centres. As a part of the Canadian Cardiovascular Society (CCS) quality initiative, the TAVI Quality Indicator (QI) Working Group was established in 2014 to develop a set of indicators to measure quality of care for Canadians undergoing TAVI for aortic stenosis. The TAVI QI Working Group is composed of expert clinical and government agency representatives. The group developed consensus agreements for the selection of the first iteration of measurable structure, process, and outcome indicators reflective of the quality of care for patients undergoing TAVI. The objectives of the project are to develop quality indicators with the eventual goal of standardizing TAVI quality reports across Canada and to support local and national quality assurance, as well as engage multiple stakeholders to build a national strategy for the evaluation of quality of care.

Clinical Profiles Related to Timing of Death, Including In-Hospital Deaths Before Admission, in Patients With ST-Elevation Myocardial Infarction.

Patients with ST-elevation myocardial infarction (STEMI) who die in hospital before inpatient admission are generally not included in clinical studies and registries, and the clinical profiles of patients who die earlier versus later are not well defined. We aimed to characterize all patients with STEMI who arrived at emergency departments in the province of Quebec (Canada) based on inpatient admission status and when they died. All patients who presented with symptoms and core laboratory-confirmed STEMI or left bundle branch block during 6 months in 82 hospitals in Quebec were included. Death certificates were used to identify nonadmitted deaths. Of the 2017 patients with STEMI, 340 (16.9%) died within 1 year. Of the latter, 63 (18.5%) were nonadmitted deaths (group A), 179 (52.6%) were deaths after admission but within 30 days (group B), and 98 (28.8%) were deaths after 30 days to 1 year (group C). Group A was younger and most often hemodynamically unstable, followed for both features by B then C. Earliest presentation from symptom onset and most frequent ambulance use were found in group A, followed by B, then C. Presenting electrocardiogram (ECG) features were most severe in A, then B, then C (more arrhythmias, more anterior STEMI, more leads with ST elevation, and higher ST elevation). Patients who died earliest had the least frequency of previous myocardial infarction, coronary revascularization, vascular disease, and heart failure, and the least noncardiac co-morbidity. In conclusion, patients with STEMI dying in hospital before inpatient admission contributed substantially to overall STEMI mortality. Although dying patients who presented earlier had severer presenting clinical profiles, they were paradoxically younger and had less co-morbidity. Previous co-morbidities may favor adaptive protective mechanisms on initial presentation with STEMI.

A new metric for centralization of ruptured abdominal aortic aneurysm repair in large territories.

OBJECTIVE: This study proposes the DEDE (Door-from-Emergency to Door-to-EVAR [endovascular aneurysm repair]) time as a new metric for ruptured abdominal aortic aneurysm (RAAA) delay time to surgery, permitting coherent centralization in large territories. It demonstrates how the DEDE time can be applied, using data from the province of Quebec, and looks at its potential effect on 30-day mortality. METHODS: We used the Quebec Integrated Chronic Disease Surveillance System (QICDSS), the linkage of five health administrative databases, to build a retrospective cohort of RAAA patients repaired operatively between April 1, 2006, and March 31, 2013. A validated algorithm was used to identify open surgical repair (OSR) and EVAR patients. Hospitals performing these operations were further characterized according to their location, volume of RAAA, types of surgeries (OSR vs EVAR), and surgeon's volume. Logistic and log-binomial regression analyses identified the risk of 30-day mortality with age, sex, hospital volume, and surgical groups as variables. Using the DEDE 90 metric and the attributable fraction, we projected how centralization and increasing the number of EVAR would affect the 30-day mortality. RESULTS: Among patients aged ≥65 years, 895 RAAAs were identified. OSR was performed in 839 patients (93.7%) and EVAR in 56 (6.3%). The overall 30-day mortality was 34.4%, and more specifically, was 35.5% for OSR compared with 17.9% for EVAR (P = .0046). RAAAs were treated in 39 hospitals, including 16 centers averaging less than one RAAA repair per year. Low-volume (39.4%) vs high-volume centers (32.5%) had similar 30-day mortality (P = .2198). In the multivariate analysis, the relative risk for OSR was 1.95 (P = .0211) and was not significant for hospital volume. Applying the DEDE 90 metric and increasing access to EVAR to 50% of patients, the overall 30-day mortality would be 26.8%. CONCLUSIONS: DEDE 90 is a new metric for a coherent centralization model, particularly in large territories, where transport time is crucial. Increasing access to EVAR performed in high-volume centers, with consideration to transport time, could improve the 30-day mortality after a RAAA repair.

Comparison of outcomes of ambulance users and nonusers in ST elevation myocardial infarction.

In a systematic province-wide evaluation of care and outcomes of ST elevation myocardial infarction (STEMI), we sought to examine whether a previously documented association between ambulance use and outcome remains after control for clinical risk factors. All 82 acute care hospitals in Quebec (Canada) that treated at least 30 acute myocardial infarctions annually participated in a 6-month evaluation in 2008 to 2009. Medical record librarians abstracted hospital chart data for consecutive patients with a discharge diagnosis of myocardial infarction who presented with characteristic symptoms and met a priori study criteria for STEMI. Linkage to administrative databases provided outcome data (to 1 year) and co-morbidities. Of 1,956 patients, 1,222 (62.5%) arrived by ambulance. Compared with nonusers of an ambulance, users were older, more often women, and more likely to have co-morbidities, low systolic pressure, abnormal heart rate, and a higher Thrombolysis In Myocardial Infarction risk index at presentation. Ambulance users were less likely to receive fibrinolysis or to be sent for primary angioplasty (78.5% vs 83.2% for nonusers, p = 0.01), although if they did, treatment delays were shorter (p <0.001). The 1-year mortality rate was 18.7% versus 7.1% for nonusers (p <0.001). Greater mortality persisted after adjusting for presenting risk factors, co-morbidities, reperfusion treatment, and symptom duration (hazard ratio 1.56, 95% confidence interval 1.30 to 1.87). In conclusion, ambulance users with STEMI were older and sicker than nonusers. Mortality of users was substantially greater after adjustment for clinical risk factors, although they received faster reperfusion treatment overall.

Impact of ECG findings and process-of-care characteristics on the likelihood of not receiving reperfusion therapy in patients with ST-elevation myocardial infarction: results of a field evaluation.

BACKGROUND: Many patients with ST-elevation myocardial infarction (STEMI) do not receive reperfusion therapy and are known to have poorer outcomes. We aimed to perform the first population-level, integrated analysis of clinical, ECG and hospital characteristics associated with non-receipt of reperfusion therapy in patients with STEMI. METHODS AND RESULTS: This systematic evaluation of STEMI care in 82 hospitals in Quebec included all patients with a discharge diagnosis of myocardial infarction, presenting with characteristic symptoms and an ECG showing STEMI as attested by at least one of two study cardiologists or left bundle branch block (LBBB). Excluding LBBB, an ECG was considered a definite STEMI diagnosis if both cardiologists scored 'certain STEMI' and ambiguous if one scored 'uncertain' or 'not STEMI'. Centers were classified according to accessibility to primary percutaneous coronary intervention (PPCI): 1) on-site PPCI; 2) routine transfer for PPCI; 3) varying mix of PPCI transfer and on-site fibrinolysis; and 4) routine on-site fibrinolysis. Of 3730 STEMI/LBBB patients, 812 (21.8%) did not receive reperfusion therapy. In multivariate analysis, likelihood of no reperfusion therapy was a function of PPCI accessibility (odds ratio [OR] for fibrinolysis versus PPCI centers = 3.1; 95% CI: 2.2-4.4), presence of LBBB (OR = 24.1; 95% CI: 17.8-32.9) and an ECG ambiguous for STEMI (OR = 4.1; 95% CI: 3.3-5.1). When the ECG was ambiguous, likelihood of no reperfusion therapy was highest in hospitals most distant from PPCI centers. CONCLUSIONS: ECG diagnostic ambiguity, LBBB and PPCI accessibility are important predictors of not receiving reperfusion therapy, suggesting opportunities for improving outcomes.

Transfer of patients with ST-elevation myocardial infarction for primary percutaneous coronary intervention: a province-wide evaluation of "door-in to door-out" delays at the first hospital.

BACKGROUND: Interhospital transfer of patients with ST-elevation myocardial infarction (STEMI) for primary percutaneous coronary intervention (PPCI) is associated with longer delays to reperfusion, related in part to turnaround ("door in" to "door out," or DIDO) time at the initial hospital. As part of a systematic, province-wide evaluation of STEMI care, we examined DIDO times and associations with patient, hospital, and process-of-care factors. METHODS AND RESULTS: We performed medical chart review for STEMI patients transferred for PPCI during a 6-month period (October 1, 2008, through March 31, 2009) and linked these data to ambulance service databases. Two core laboratory cardiologists reviewed presenting ECGs to identify left bundle-branch block and, in the absence of left bundle-branch block, definite STEMI (according to both cardiologists) or an ambiguous reading. Median DIDO time was 51 minutes (25th to 75th percentile: 35-82 minutes); 14.1% of the 988 patients had a timely DIDO interval (≤30 minutes as recommended by guidelines). The data-to-decision delay was the major contributor to DIDO time. Female sex, more comorbidities, longer symptom duration, arrival by means other than ambulance, arrival at a hospital not exclusively transferring for PPCI, arrival at a center with a low STEMI volume, and an ambiguous ECG were independently associated with longer DIDO time. When turnaround was timely, 70% of patients received timely PPCI (door-to-device time ≤90 minutes) versus 14% if turnaround was not timely (P<0.0001). CONCLUSIONS: Benchmark DIDO times for STEMI patients transferred for PPCI were rarely achieved. Interventions aimed at facilitating the transfer decision, particularly in cases of ECGs that are difficult to interpret, are likely to have the best impact on reducing delay to reperfusion.

Should eligibility for heart transplantation be a requirement for left ventricular assist device use? Recommendations based on a systematic review.

Left ventricular assist devices (LVADs) are used in chronic end-stage heart failure as "bridge to transplantation" (BTT) and, more recently, for transplant-ineligible patients as "destination therapy" (DT). We reviewed the evidence on clinical effects and cost-effectiveness of 2 types of continuous-flow LVADs (HeartMate II [HM II] and HeartWare), for BTT and DT patients. We systematically searched the scientific literature (January 2008-June 2012) and identified 14 clinical studies (approximately 2900 HM II and approximately 200 HeartWare patients), and 3 economic evaluations (HM II) using simulation models. Data were, however, limited to 2-3 studies per outcome. We made policy recommendations on the basis of our systematic review. Although complications after implantation are frequent, LVAD therapy is often highly effective across transplantation eligibility status and device, with 1-year survival reaching 86% for BTT and 78% for DT (compared with 25% for medical therapy). Neither BTT nor DT currently meet traditional cost-effectiveness limits in models using historical data, although BTT is standard practice for a limited number of patients in many regions. We found that BTT and DT as implantation strategies tend to be no longer mutually exclusive. We conclude that evidence is sufficient to support LVAD use, regardless of transplantation eligibility status, as long as patients are carefully selected and program infrastructure and budget are adequate. However, evidence gaps, limitations in economic models, and the lack of Canadian data point to the importance of mandatory, systematic monitoring of LVAD use and outcomes.

Transcatheter aortic valve implantation: recommendations for practice based on a multidisciplinary review including cost-effectiveness and ethical and organizational issues.

Transcatheter aortic valve implantation (TAVI) is a relatively new technology for the treatment of severe and symptomatic aortic valve stenosis. TAVI offers an alternative therapy for patients unable to be treated surgically because of contraindications or severe comorbidities. It is being rapidly dispersed in Canada, as it is worldwide. The objective of this article is to present our recommendations for the use of TAVI, based on a multidisciplinary evaluation of recently published evidence. We systematically searched and summarized published data (2008-2011) on benefits, risks, and cost-effectiveness of TAVI. We also examined ethical issues and organizational aspects of delivering the intervention. We discussed the soundness and applicability of our recommendations with clinical experts active in the field. The published TAVI results for high-risk and/or inoperable patients are promising in terms of survival, function, quality of life, and cost-effectiveness, although we noted large variability in the survival rates at 1 year and in the frequency of important adverse outcomes such as stroke. Until more data from randomized controlled trials and registries become available, prudence and discernment are necessary in the choice of patients most likely to benefit. Patients need to be well-informed about gaps in the evidence base. Our recommendations support the use of TAVI in the context of strict conditions with respect to patient eligibility, the patient selection process, organizational requirements, and the tracking of patient outcomes with a mandatory registry.

Symptoms of impairment, disability and handicap in low back pain: a taxonomy.

The functional consequences on everyday living which result from chronic low back pain commonly require services which are difficult to access. This deficiency in meeting the needs of these patients is partially explained by inadequacies in clinical assessment. Medical evaluation may be exhaustive, but frequently the assessment of physical and psycho-social dysfunction at the personal and family level is inadequate. In low back pain, as with most chronic ailments, there is no agreed-upon taxonomy of the functional consequences of the disorder upon which to establish a comprehensive clinical appraisal. In this paper a taxonomy is presented for the impairments, disabilities and handicaps which result from chronic low back pain. The taxonomy has been based on data from a survey of 74 individuals with low back pain and is structured generally according to the International Classification of Impairments, Disabilities and Handicaps (WHO 1980). The taxonomy is proposed as a conceptual framework and vocabulary for both clinical practice and research. The taxonomy is not a measurement instrument nor does it indicate the frequency of occurrence of disabilities. A classification is basic to the advancement of scientific understanding, and usage of a standard vocabulary such as this plays an important role in establishing a responsive health service capable of meeting the needs of the population with chronic low back pain.