Can we monitor heart attack in the troponin era: evidence from a population-based cohort study

Table 1 Hierarchical classification of cardiovascular discharge diagnoses in non-fatal cases which identified the validation population and sample

Diagnosis	ICD codes		1998		2003
	ICD-9-CM	ICD-10-AM	Counts (n = 8939)	% Troponin tests^a	Counts (n = 9188)	% Troponin tests^a
MI^b	410	I21, I22	1425	81	1582	97
Unstable angina^b	411.1	I20.0	2024	53	1507	93
Other IHD^c
Other Angina	other 411, 413	other I20	620	37	548	75
Other IHD	rest of 410-414	I24, I25	135	15	216	54
Other CVD^c
Heart Failure	428	I50	820	32	655	79
Valve Disorders	424.0, 424.1	I34, I35	59	19	66	29
Arrhythmia	427	I46-I49	1557	21	1723	46
Hypertension	401-405	I10-I15	159	4	100	30
Other cardiovascular	rest of 401-429	rest of I10-I52	515	20	514	51
Chest pain^c	786.5	R07	1625	46	2277	82

Cases were based on 28-day episodes of care. CVD: cardiovascular disease; ICD: International Classification of Diseases; IHD: ischaemic heart disease.
^a % troponin tests = proportion of cases who had at least one troponin test.
^b From any diagnosis field of the HMDC (Hospital Morbidity Data Collection).
^c From principal diagnosis field of the HMDC.

ISSN: 1471-2261