There is a wide variation in reported accuracy ofnoninvasive stress myocardial imaging as a screening tool for coronary artery disease (CAD). This study was undertaken to determine its current accuracy in a wide spectrum of patients with chest pain syndromes using invasive coronary angiography as the gold standard.
The patient population consisted of consecutive patients undergoing coronary angiography in whom noninvasive stress imaging, either nuclear or echocardiographic, was performed within 6 months prior to the angiogram. The specificity, sensitivity, positive and negative predictive values, and diagnostic accuracy for detecting > or =1 lesions with > or =50% diameter coronary stenosis were determined for each modality.
Of the 227 eligible patients, 141 were men and 86 were women; 70% had significant CAD. The diagnostic accuracy overall was 71% and was no different for nuclear or echocardiographic testing. The positive predictive value (86% vs. 52%; P = 0.002) and diagnostic accuracy (83% vs. 51%; P = 0.002) were better in men than in women.
In this study, noninvasive stress imaging lacked the accuracy of a good screening test for significant CAD. This finding was particularly true for women, for whom it was not much better than a coin toss.
Aerobic exercise intensity assessment and prescription in cardiac rehabilitation: a joint position statement of the European Association for Cardiovascular Prevention and Rehabilitation, the American Association of Cardiovascular and Pulmonary Rehabilitation and the Canadian Association of Cardiac Rehabilitation.
Aerobic exercise intensity prescription is a key issue in cardiac rehabilitation, being directly linked to both the amount of improvement in exercise capacity and the risk of adverse events during exercise. This joint position statement aims to provide professionals with up-to-date information regarding the identification of different exercise intensity domains, the methods of direct and indirect determination of exercise intensity for both continuous and interval aerobic training, the effects of the use of different exercise protocols on exercise intensity prescription and the indications for recommended exercise training prescription in specific cardiac patients' groups. The importance of functional evaluation through exercise testing prior to starting an aerobic training program is strongly emphasized, and ramp incremental cardiopulmonary exercise test, when available, is proposed as the gold standard for a physiologically comprehensive exercise intensity assessment and prescription. This may allow a shift from a 'range-based' to a 'threshold-based' aerobic exercise intensity prescription, which, combined with thorough clinical evaluation and exercise-related risk assessment, could maximize the benefits obtainable by the use of aerobic exercise training in cardiac rehabilitation.
In 2014, the Swedish Association of Clinical Physiology recommended the use of a new reference material for exercise capacity in bicycle exercise stress testing, 'the Kalmar material'. Compared to the formerly used reference material, 'the Kristianstad material', an increase in the amount of patients being classified as having decreased exercise capacity was expected, but the extent of this in clinical practice is not known.
Results of exercise capacity from 1449 bicycle exercise tests, in patients aged =20 years (656 women, 793 men) performed at two departments of Clinical Physiology before and after change of reference materials, were collected. Maximal workload was related to the predicted values of both reference materials. If made, recommendations for supplemental nuclear myocardial perfusion imaging study by the attending physician were noted.
Using the new reference material, 31% of all patients were classified as having a decreased exercise capacity, compared to 17% using the formerly used reference material. The difference between the two reference materials was largest in the older age groups. In one of the departments, an increase in recommendations of supplemental myocardial perfusion studies was seen after introduction of the new reference material, whereas the opposite was seen at the other department.
A large amount of patients are being classified as having decreased exercise capacity and very few as having good exercise capacity using the new reference material for exercise capacity.
Cardiopulmonary exercise testing (CPET) is the gold standard among clinical exercise tests. It combines a conventional stress test with measurement of oxygen uptake (VO2 ) and CO2 production. No validated Swedish reference values exist, and reference values in women are generally understudied. Moreover, the importance of achieved respiratory exchange ratio (RER) and the significance of breathing reserve (BR) at peak exercise in healthy individuals are poorly understood. We compared VO2 at maximal load (peakVO2 ) and anaerobic threshold (VO2@AT ) in healthy Swedish individuals with commonly used reference values, taking gender into account. Further, we analysed maximal workload and peakVO2 with regard to peak RER and BR. In all, 181 healthy, 50-year-old individuals (91 women) performed CPET. PeakVO2 was best predicted using Jones et al. (100·5%), while SHIP reference values underestimated peakVO2 most: 112·5%. Furthermore, underestimation of peakVO2 in women was found for all studied reference values (P 1·1 (2 328·7 versus 2 176·7 ml min-1 , P = 0·11). Lower BR (=30%) related to significantly higher peakVO2 (P 1·1 in healthy individuals was found. A lowered BR is probably a normal response to higher workloads in healthy individuals.
A simple 2-km Walking Test has been developed for determining the cardiorespiratory fitness of healthy adults. In the present study the following aspects of the feasibility of this test for population assessment were investigated: participation willingness, the percentage of test qualified subjects, the percentage of acceptable test performances and the resources needed for field test administration. A representative sample was drawn from the 27 to 65-year-old population in a rural municipality in northeastern Finland. Subjects were recruited on the basis of the results of health questionnaires and interviews. One fourth of the volunteers were excluded from the test because of health problems. The 2-km walking tests were administered outdoors in the municipality center. More than 50% of the subjects successfully completed two consecutive walking tests. This study indicated that the 2-km Walking Test is a feasible alternative as a measure of cardiovascular fitness for large population groups and could potentially be used in exercise related health promotion programmes.
BACKGROUND: The definition or diagnosis of asthma is a challenge for both clinicians and epidemiologists. Symptom history is usually supplemented with tests of bronchial hyperresponsiveness (BHR) in spite of their uncertainty in improving diagnostic accuracy. METHODS: To assess the interrelationship between respiratory symptoms, BHR, and clinical diagnosis of asthma, the respiratory symptoms of 1633 schoolchildren were screened using a questionnaire (response rate 81.2%) and a clinical study was conducted in a subsample of 247 children. Data from a free running test and a methacholine inhalation challenge test were available in 218 children. The diagnosis of asthma was confirmed by a paediatric allergist. RESULTS: Despite their high specificity (>0.97), BHR tests did not significantly improve the diagnostic accuracy after the symptom history: area under the receiver operator characteristic (ROC) curve was 0.90 for a logistic regression model with four symptoms and 0.94 for the symptoms with free running test and methacholine inhalation challenge results. On the other hand, BHR tests had low sensitivity (0.35-0.47), whereas several symptoms had both high specificity (>0.97) and sensitivity (>0.7) in relation to clinical asthma, which makes them a better tool for asthma epidemiology than BHR. CONCLUSIONS: Symptom history still forms the basis for defining asthma in both clinical and epidemiological settings. BHR tests only marginally increased the diagnostic accuracy after symptom history had been taken into account. The diagnosis of childhood asthma should not therefore be overlooked in symptomatic cases with no objective evidence of BHR. Moreover, BHR should not be required for defining asthma in epidemiological studies.
A modification of the Astrand (1960) nomogram procedure was applied to Canadian Home Fitness Test data obtained on 13,258 subjects, ages 15 to 69 years, during the 1981 Canada Fitness Survey. Norms were developed to allow an empirical five-level categorization of aerobic fitness, based on the attained rate of stepping and the recovery pulse count 5 to 15 s following exercise. Because of uncertainties regarding the net mechanical efficiency of stepping and the selective recruitment of fit older subjects, the apparent rate of aerobic fitness decrease with aging was no more than half of that seen in laboratory measurements, and the sex differential at any given age (about 25%) was larger than expected. The new approach thus does not claim a high level of accuracy for the predicted peak MET values. Nevertheless, it has an inherent advantage over the equation of Jetté et al. (1976) in that it takes more direct account of variations in pulse count when categorizing fitness. Moreover, there is no artificial ceiling that limits scores for very fit subjects. Tests are now needed to assess the accuracy of the proposed fitness categorizations relative to laboratory determinations of maximal oxygen intake.
Notes
Comment In: Can J Appl Physiol. 1994 Mar;19(1):103-78186761
Comment In: Can J Appl Physiol. 1994 Jun;19(2):226-348081325
Procedures for the preliminary screening of asymptomatic adults who wish to exercise are reviewed with particular reference to experience gained through the mass use of the physical activity readiness questionnaire (PAR-Q) and the Canadian Home Fitness Test (CHFT). It is argued that both a brief submaximal exercise test and a subsequent moderate increase of habitual activity are extremely safe tactics to recommend to a symptom-free adult. There are some useful minor modifications which could be made to the PAR-Q instrument, but its sensitivity and specificity relative to such criteria as medical examination, hypertension, CHFT completion and exercise-induced ECG abnormalities compare favourably with alternative self-administered procedures. The basic difficulty of screening an asymptomatic population (highlighted by Bayes theorem) is the high percentage of false positive and false negative test results. One remedy would be to stratify the population in terms of known cardiac risk factors and to restrict detailed pre-exercise screening to the high risk segment of the population.
