Comparison between FEV1/FEV6 and FEV1/FVC as screening of chronic obstructive pulmonary disease

OBJECTIVE

To compare FEV₁/FEV₆ to the standard spirometry (FEV₁/FVC) as a screening tool for COPD.

METHODS

This cross-sectional study was conducted at Hospital Tuanku Fauziah, Perlis, Malaysia from August 2015 to April 2016. FEV₁/FEV₆ and FEV₁/FVC results of 117 subjects were analysed. Demographic data and spirometric variables were tabulated. A scatter plot graph with Spearman's correlation was constructed for the correlation between FEV₁/FEV₆ and FEV1/FVC. The sensitivity, specificity, positive and negative predictive values of FEV₁/FEV₆ were determined with reference to the gold standard of FEV₁/FVC ratio <0.70. Receiver-operator characteristic (ROC) curve analysis and Kappa statistics were used to determine the FEV₁/FEV₆ ratio in predicting an FEV₁/FVC ratio <0.70.

RESULTS

Spearman's correlation with r = 0.636 (P<0.001) was demonstrated. The area under the ROC curve was 0.862 (95% confidence interval [CI]: 0.779 - 0.944, P<0.001). The FEV₁/FEV₆ cut-off with the greatest sum of sensitivity and specificity was 0.75. FEV₁/FEV₆ sensitivity, specificity, positive and negative predictive values were 93.02%, 67.74%, 88.89% and 77.78% respectively. There was substantial agreement between the two diagnostic cut-offs (κ = 0.634; 95% CI: 0.471 - 0.797, P<0.001) CONCLUSIONS: The FEV₁/FEV₆ ratio can be considered to be a good alternative to the FEV₁/FVC ratio for screening of COPD. Larger multicentre study and better education on spirometric techniques can validate similar study outcome and establish reference values appropriate to the population being studied.

Chronic nephrotoxicity of anti-inflammatory drugs used in the treatment of arthritis

We determined the consumption of non-steroidal anti-inflammatory drugs (NSAIDs) and the prevalence of chronic renal impairment and renal papillary necrosis (RPN) in patients with various types of arthritis. Ninety-four patients with chronic arthritis who had consumed more than 1000 capsules and/or tablets of NSAIDs were studied. Renal profiles and radiological investigations such as intravenous urogram (IVU), ultrasonography (US) and computed tomography (CT) were performed to look for evidence of RPN. Twelve patients did not complete the study. Ten of the 82 patients who had completed the study (12.2%) had radiologic evidence of RPN. Five out of 53 patients (9.4%) with rheumatoid arthritis, three out of 11 patients (27.3%) with gouty arthritis and two out of seven patients (28.6%) with osteoarthritis had RPN. Renal impairment (serum creatinine levels of 125-451 mumol/l) was found in 20 patients (24.4%). The patients had consumed 1000-26,300 capsules and/or tablets over a period ranging from 1 yr to more than 30 yr. Patients with chronic arthritis who consume excessive amount of NSAIDs are at risk of developing RPN and chronic renal impairment.