Accuracy of diagnosis and classification of COPD in primary and specialist nurse-led respiratory care in Rotherham, UK: a cross-sectional study.

BACKGROUND: Studies have suggested that chronic obstructive pulmonary disease (COPD) is commonly misdiagnosed and misclassified in primary care, but less is known about the quality of diagnosis in specialist respiratory care. AIMS: To measure the accuracy of COPD diagnosis and classification of airway obstruction in primary care and at a specialist respiratory centre, and to explore associations between misdiagnosis and misclassification and a range of explanatory factors. METHODS: Data were obtained for 1,205 referrals to a specialist respiratory centre between 2007 and 2010. Standard analysis methods were used. RESULTS: The majority of patients were referred for pulmonary rehabilitation (676/1,205, 56%). Of 1,044 patients with a primary care diagnosis of COPD, 211 (20%) had spirometry inconsistent with COPD. In comparison, of 993 specialist centre diagnoses, 65 (6.5%) had inconsistent spirometry. There was poor agreement between the airflow obstruction grade recorded on the referral and that based on spirometry (kappa=0.26, n=448), whereas agreement between the respiratory centre assessment of airflow obstruction and spirometry was good (kappa=0.88, n=1,016). Referral by practice nurse was associated with accuracy of airflow obstruction classification in primary care (OR 1.85, 95% CI 1.33 to 2.57). Males were more likely than females to have an accurate specialist care classification of airway obstruction (OR 1.40, 95% CI 1.01 to 1.93). Grade of airway obstruction changed between referral and assessment in 56% of cases. CONCLUSIONS: In primary care, a proportion of patients diagnosed with COPD do not have COPD, and misclassification of grade of airflow obstruction is common. Misdiagnosis and misclassification is less common in the specialist care setting of BreathingSpace.

Is a large scale community programme as effective as a community rehabilitation programme delivered in the setting of a clinical trial?

BACKGROUND: The rationale for commissioning community pulmonary rehabilitation programmes is based on evidence from randomised clinical trials. However, there are a number of reasons why similar programmes might be less effective outside the environment of a clinical trial. These include a less highly selected patient group and less control over the fidelity of intervention delivery. The main objective of this study was therefore to test the hypothesis that the real-world programme would have similar outcomes to an intervention delivered in the context of a clinical trial. METHODS: As part of the evaluation of an innovative community-based pulmonary rehabilitation programme ("BreathingSpace"), clinical and quality of life measures were collected before and after delivery of a rehabilitation programme. Baseline characteristics of participants and the change in symptoms and quality of life after the BreathingSpace programme were compared to measures collected in the community-based arm of a separate randomised trial of pulmonary rehabilitation. RESULTS: Despite differences between the BreathingSpace participants and research participants in clinical status at baseline, patient reported symptoms and quality of life measures were similar. Improvements in both symptoms and quality of life were of the same order of magnitude despite the different contexts, setting and scale of the two intervention programmes. Whilst 73% (326/448) of those considered suitable for community rehabilitation in the trial and 80% (393/491) assessed as suitable for the BreathingSpace programme agreed to participate, less than half of participants completed rehabilitation, whether in a research or "real world" setting (47% and 45% respectively). CONCLUSION: The before-after changes in outcomes seen in a "real world" community rehabilitation programme are similar in magnitude to those seen in the intervention arm of a clinical trial. However suboptimal uptake and high dropout rates from rehabilitation amongst eligible participants occurs in both clinical trials and community based programmes and must be addressed if the benefits of rehabilitation for people with chronic lung disease are to be maximised.

Do we need all three criteria for the diagnostic separation of pleural fluid into transudates and exudates? An appraisal of the traditional criteria.

BACKGROUND: Classification of pleural effusions into transudates and exudates is based on pleural fluid absolute lactic dehydrogenase value (FLDH), fluid to serum ratio of LDH (LDHR) and fluid to serum ratio of total protein (TPR) used in a parallel combination strategy. Combining multiple tests in a parallel strategy to improve diagnostic accuracy is useful only if the pair-wise correlation of the individual tests is less than 0.75. So far, this concept has not been tested in patients with pleural effusions. MATERIAL/METHODS: Biochemical data from our 200-patient series with a known cause of pleural effusion were included in this study. Correlation between the three possible combinations of tests was determined. RESULTS: There were 116 males and 84 females. The mean age was 62+/-1.1 years (mean+/-SEM). Of the 200 effusions, 156 were exudates and 44 were transudates. There was a significant correlation between FLDH and LDHR (r=0.93, p<0.00). However, the correlation between FLDH and TPR (r=0.27) and TPR and LDHR (r=0.22) was not significant. CONCLUSIONS: The operative mechanism for LDHR and FLDH used in the classification of transudate and exudates appears to be similar, and therefore unsuitable for a parallel combination strategy in the diagnostic separation of pleural effusion. FLDH and TPR have a dissimilar operating mechanism, and can therefore be combined in this process. Therefore, the diagnostic separation of pleural effusion can be done cost effectively by utilizing FLDH and TPR alone, as the cost for estimating serum LDH is eliminated in this approach.

Is albumin gradient or fluid to serum albumin ratio better than the pleural fluid lactate dehydroginase in the diagnostic of separation of pleural effusion?

BACKGROUND: To determine the accuracy of serum-effusion albumin gradient (SEAG) and pleural fluid to serum albumin ratio (ALBR) in the diagnostic separation of pleural effusion into transudate and exudate and to compare SEAG and ALBR with pleural fluid LDH (FLDH) the most widely used test. METHODS: Data collected from 200 consecutive patients with a known cause of pleural effusion in a United Kingdom district general hospital. RESULTS: The median and inter quartile ranges (IQR) for SEAG 93.5 (33.8 to 122.5) g/dl, ALBR 0.49 (0.42 to 0.62) and FLDH 98.5 IU/L(76.8 to 127.5) in transudates were significantly lower than the corresponding values for exudates 308.5 (171 to 692), 0.77 (0.63 to 0.85), 344 (216 to 695) all p < 0.0001. The Area Under the Curve (AUC) with 95% confidence intervals (Cl) for SEAG, ALBR and FLDH were 0.81 (0.75 to 0.87), 0.79 (0.72 to 0.86) and 0.9 (0.87 to 0.96) respectively. The positive likelihood ratios with 95%CI for FLDH, SEAG, and ALBR were: 7.3(3.5-17), 6.3(3-15) 6.2(3-14) respectively. There was a significant negative correlation between SEAG and ALBR (r= -0.89, p < 0.0001). CONCLUSION: The discriminative value for SEAG and ALBR appears to be similar in the diagnostic separation of transudates and exudates. FLDH is a superior test compared to SEAG and ALBR.