Precise value of EXACT in COPD uncertain

EXACT (Exacerbations of Chronic Obstructive Pulmonary Disease [COPD] Tool) is effective in assessing exacerbations of the disease in the outpatient setting, a study shows.

However, the findings also cast doubt over the ability of the daily patient diary to accurately detect exacerbations, with only one-third of those picked up by other means meeting the pre-specified criteria for an EXACT event.

“EXACT scores increase at COPD exacerbation, the magnitude of which reflects the severity of the event in terms of treatment, systemic inflammation, airflow limitation and symptom recovery time,” say authors Alex Mackay (University College London, UK) and colleagues.

However, they add, “this study has highlighted important potential limitations of the EXACT in its ability to independently identify events which were captured by physician review (HCU [healthcare utilization]) or London COPD cohort diary cards.”

The study involved 58 patients enrolled in the London COPD cohort between January 2010 and April 2012. Patients recorded their daily peak expiratory flow rate and any increase in respiratory symptoms in the validated London COPD cohort diary cards, as well as recording their daily symptoms in the EXACT diary every evening before bedtime.

In the 8 to 14 days prior to exacerbation onset (baseline), according to the London COPD cohort diary, the average EXACT score over 7 days was 42.6. This increased to 48.0 at exacerbation onset, equating to a 13% rise, and reached a maximum of 54.1 during the 2 weeks following exacerbation onset.

Baseline EXACT scores were also significantly related to disease severity according to exacerbation frequency, forced expiratory volume in 1 second (FEV1) and % predicted FEV1. And, the change in EXACT score from baseline to exacerbation correlated with systemic inflammation, as shown by C-reactive protein levels.

Additionally, EXACT scores accurately reflected exacerbation recovery, showing good concordance with recovery time according to the London COPD cohort diary cards (median 7 vs 8 days).

However, Mackay and team found only a “modest” relationship between exacerbations defined by the EXACT score (persistent 9–12-point increase over 2–3 days) and those defined by HCU and the London Cohort diary card. Only 21.1 to 26.6% of the 128 exacerbations recorded by the London cohort diary were detected by EXACT, as were 25.9 to 34.1% of the 85 exacerbations requiring HCU.

Writing in the European Respiratory Journal, the authors say their findings support EXACT in the assessment of exacerbation severity. However, they conclude that “uncertainty remains regarding the effectiveness of the instrument to independently and accurately detect the onset and frequency of exacerbations, a particular concern in the study of preventative therapies for COPD exacerbations.”

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