Table S4.

PPV and sensitivity of CPRD strategies to identify hospitalizations for AECOPD using different HES definitions as reference standard allowing 60 days after HES record of hospitalization for AECOPD

HES AECOPD definition	CPRD strategy	PPV (95% CI)	Sensitivity (95% CI)
AECOPD hospitalization code or LRTI code in any position or COPD in the first position in any FCE	AECOPD hospitalization code	50.7% (49.1–52.3)	4.4% (4.3–4.6)
	AECOPD identified using validated algorithm and hospitalization code	46.1% (44.3–47.8)	6.1% (5.8–6.4)
Either specific AECOPD code in any position or COPD code in the first position	AECOPD hospitalization code	49.5% (48.0–51.1)	5.0% (4.8–5.3)
	AECOPD identified using validated algorithm and hospitalization code	41.2% (39.5–42.9)	6.2% (5.9–6.6)
Either specific AECOPD code in the first position in any FCE	AECOPD hospitalization code	46.6% (45.0–48.2)	5.0% (4.8–5.3)
	AECOPD identified using validated algorithm and hospitalization code	39.5% (37.8–41.2)	6.4% (6.1–6.8)

Abbreviations: CI, confidence interval; COPD, chronic obstructive pulmonary disease; AECOPD, acute exacerbations of COPD; LRTI, lower respiratory tract infection; HES, Hospital Episodes Statistics; FCE, finished consultant episodes; CPRD, Clinical Practice Research Datalink; PPV, positive predictive value.