Different Case Finding Approaches to Optimise COPD Diagnosis: Evidence from the RADICALS Trial

Abstract

Aim

Diagnosis of COPD in primary care is hindered by underuse of spirometry. Case finding using validated symptom and health status questionnaires, and simple handheld devices in high-risk populations may improve diagnosis. This study aimed to determine the best combination of measures to optimise COPD diagnosis in the primary care setting.

Methods

We recruited 335 current or ex-smokers, including those with an established diagnosis of COPD from general practices. Participants’ FEV₁ and FEV₆ were measured using a handheld spirometry device (COPD-6^®). Each completed the COPD assessment test (CAT), a modified Medical Research Council (mMRC) dyspnoea scale, St George’s Respiratory Questionnaire (SGRQ) and smoking history questionnaire. From these data we calculated the predictive validity for spirometry-confirmed diagnosis of COPD. Area under the receiver operating characteristic curve (AUROC), sensitivity, specificity, positive and negative predictive values (PPV, NPV) were calculated for each. Kappa coefficient was used to measure the agreement between the Fixed-Ratio (FR) and Lower Limit of Normal (LLN) spirometric criteria in diagnosing COPD.

Results

FEV₁/FEV₆ <0.70 alone showed significant association (p<0.0001) with COPD diagnosis and good predictive accuracy (AUROC=0.725). However, no further improvement was found after combining SGRQ, CAT and mMRC with FEV₁/FEV₆. FEV₁/FEV₆ <0.70 using the COPD-6^® handheld device had moderate sensitivity (65.7%) and high PPV (90.1%), high specificity (79.3%) and NPV (44.8%). There was good agreement between FR and LLN definitions (κ=0.70).

Conclusion

Handheld micro-spirometers can facilitate case finding of COPD in smokers and ex-smokers attending general practice. The fixed ratio criterion currently recommended by COPD-X guidelines offers the simplest method for diagnosing COPD in Australian primary care.

Keywords:

• case finding
• COPD
• diagnosis
• primary care

Take Home Messages

• Case finding using handheld spirometers at a cut-off of FEV₁/FEV₆ < 0.70 gives the best sensitivity and specificity for COPD diagnosis.

• Use of symptoms and COPD-related quality of life questionnaires add little value to FEV₁/FEV₆ -based case finding.

• Fixed-cut-off ratio and the lower limit of normal (LLN) definitions for characterising airflow limitation provide comparable results when used to diagnose COPD in the primary care setting.

Data Sharing Statement

The raw data on which conclusions of this manuscript rely are available upon reasonable requests. The overall results are available as part of the manuscript and Supplementary Tables, but if individual data points are needed, this could be provided in response to a reasonable request.

Ethics Approval and Informed Consent

The institutional Ethics Committee approved the RADICALS trial (Monash University CF14/1018 –2014000433). Informed written consent was obtained from each participant before the trial commencement. The study was conducted in accordance with Good Clinical Practice guidelines and the provisions of the Declaration of Helsinki. RADICALS trial registration number is ACTRN12614001155684.

Acknowledgments

We wish to thank the RADICALS Data Safety and Monitoring Board members (Ian Yang, Jennifer Alison and Julia Walters), Jenifer Liang, Denise van den Bosch, Jessica Webster, Rita Breare, Mieke Hutchinson-Kern, The Alfred Respiratory Laboratory, Eleonora Del Colle and Pulmetrics staff, Brian Meier, Eli Dabscheck, Agape Stratigis, Amanda Cross, Amanda Nichols, Andrew Clayton, Caroline Nicolson, Francesca Sgroi, Georgia Lakoumentas, Hilary Edwards, Janet Carberry, Jannette Angell, Kay Dunkley, Lisa Austin, Melanie Frodsham, Robyn Saunders, Robyn Stell, Ross de Gori, Rosemary Moore, Sandy Scholes, Sarah Rawlings, Tamara Ford, Yamuna Prashanth, research students, clinic staff and participants for their help with the RADICALS trial. Muhammad Rehan Sarwar assisted with responding to reviewer comments.

Disclosure

Mr Nawar Alotaibi reports grants from Pfizer, grants from Sanofi and GSK, during the conduct of the study; Ms Brigitte M Borg reports personal fees from Wiley Blackwell Publishing, outside the submitted work; Professor Michael J Abramson reports grants from Boehringer-Ingelheim, during the conduct of the study; grants from Pfizer, grants from Sanofi, grants from GSK, personal fees, personal fees from GSK, outside the submitted work; Professor Anne E Holland reports grants from National Health and Medical Research Council (Australia), grants from Boehringer Ingelheim Pty Ltd, non-financial support from Eastern Melbourne Primary Health Network (PHN), non-financial support from Lung Foundation Australia, during the conduct of the study; Dr Johnson George reports grants, non-financial support from Boehringer Ingelheim, during the conduct of the study; grants, grants from GSK, grants, grant from Pfizer, outside the submitted work. The authors report no other conflicts of interest in this work.