Accuracy and Quality of Spirometry in Primary Care Offices.

RATIONALE: Spirometry is necessary for the optimal management of patients with respiratory disease. The quality of spirometry performed in the primary care setting has been inconsistent. OBJECTIVES: We aimed to evaluate spirometer accuracy, determine the clinical significance of inaccurate spirometers, and assess the quality of spirograms obtained in primary care offices. METHODS: We tested 17 spirometers used in primary care offices with a waveform generator; accuracy and precision were assessed using American Thoracic Society criteria. The clinical significance of inaccurate instruments was determined by applying the FEV1/FVC error from an obstructed waveform to a clinical data set. Spirogram quality was determined by grading spirograms using acceptability and repeatability criteria. The relationship between the number of tests performed by a clinic and test quality was assessed. MEASUREMENTS AND MAIN RESULTS: Only 1 of 17 spirometers met accuracy criteria, with mean errors for FVC, FEV1, and FEV1/FVC ranging from 1.7 to 3.1%. Applying the percentage error to a clinical data set resulted in 28% of tests being recategorized from obstructed to nonobstructed. Of the spirograms reviewed, 60% were considered acceptable for clinical use. There was no association between the number of tests performed by a clinic and spirometry quality. CONCLUSIONS: Most spirometers tested were not accurate. The magnitude of the errors resulted in significant changes in the categorization of patients with obstruction. Acceptable-quality tests were produced for only 60% of patients. Our results raise concerns regarding the utility of spirometry obtained in primary care offices without greater attention to quality assurance and training.

Apixaban for the Secondary Prevention of Thrombosis Among Patients With Antiphospholipid Syndrome: Study Rationale and Design (ASTRO-APS).

BACKGROUND: Antiphospholipid syndrome (APS) is an acquired thrombophilia characterized by thrombosis, pregnancy morbidity, and the presence of characteristic antibodies. Current therapy for patients having APS with a history of thrombosis necessitates anticoagulation with the vitamin K antagonist warfarin, a challenging drug to manage. Apixaban, approved for the treatment and prevention of venous thrombosis with a low rate of bleeding observed, has never been studied among patients with APS. AIMS AND METHODS: We report study rationale and design of Apixaban for the Secondary Prevention of Thrombosis Among Patients With Antiphospholipid Syndrome (ASTRO-APS), a prospective randomized open-label blinded event pilot study that will randomize patients with a clinical diagnosis of APS receiving therapeutic anticoagulation to either adjusted-dose warfarin or apixaban 2.5 mg twice a day. We aim to report our ability to identify, recruit, randomize, and retain patients with APS randomized to apixaban compared with warfarin. We will report clinically important outcomes of thrombosis and bleeding. All clinical outcomes will be adjudicated by a panel blinded to the treatment arm. A unique aspect of this study is the enrollment of patients with an established clinical diagnosis of APS. Also unique is our use of electronic medical record interrogation techniques to identify patients who would likely meet our inclusion criteria and use of an electronic portal for follow-up visit data capture. CONCLUSION: ASTRO-APS will be the largest prospective study to date comparing a direct oral anticoagulant with warfarin among patients with APS for the secondary prevention of thrombosis. Our inclusion criteria assure that outcomes obtained will be clinically applicable to the routine management of patients with APS receiving indefinite anticoagulation.

Single-breath diffusing capacity for carbon monoxide instrument accuracy across 3 health systems.

BACKGROUND: Measuring diffusing capacity of the lung for carbon monoxide (DLCO) is complex and associated with wide intra- and inter-laboratory variability. Increased D(LCO) variability may have important clinical consequences. The objective of the study was to assess instrument performance across hospital pulmonary function testing laboratories using a D(LCO) simulator that produces precise and repeatable D(LCO) values. METHODS: D(LCO) instruments were tested with CO gas concentrations representing medium and high range D(LCO) values. The absolute difference between observed and target D(LCO) value was used to determine measurement accuracy; accuracy was defined as an average deviation from the target value of < 2.0 mL/min/mm Hg. Accuracy of inspired volume measurement and gas sensors were also determined. RESULTS: Twenty-three instruments were tested across 3 healthcare systems. The mean absolute deviation from the target value was 1.80 mL/min/mm Hg (range 0.24-4.23) with 10 of 23 instruments (43%) being inaccurate. High volume laboratories performed better than low volume laboratories, although the difference was not significant. There was no significant difference among the instruments by manufacturers. Inspired volume was not accurate in 48% of devices; mean absolute deviation from target value was 3.7%. Instrument gas analyzers performed adequately in all instruments. CONCLUSIONS: D(LCO) instrument accuracy was unacceptable in 43% of devices. Instrument inaccuracy can be primarily attributed to errors in inspired volume measurement and not gas analyzer performance. D(LCO) instrument performance may be improved by regular testing with a simulator. Caution should be used when comparing D(LCO) results reported from different laboratories.