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Abstract
The object of this study was to evaluate the sensitivity and positive predictive value (PPV) of International Classification of Diseases, 9th revision (ICD-9) codes 430-438 in the Sistema Informativo Sanitario Regionale (SISR), an Italian health care automated database. We compared the SISR with a manual search of all cases of transient ischaemic attack (TIA) and stroke discharged from the Novara Hospital, NW Italy. Results were as follows: SISR list: 1017 patients; manual list 1005. Linked: 896; false negatives: 109; false positives: 121. Sensitivity of codes 430-438: 77% at the primary position only and 89% at either the primary or secondary position; PPV: 93% and 88%. Sensitivity and PPV for specific codes vs. each subcategory (sensitivity at the primary position only/any position; PPV at the primary position only/any position): for 430, subarachnoid haemorrhage (33/35%; 46/43%); for 431, cerebral haemorrhage (57/59%; 77/75%); for 434, cerebral infarction (35/37%; 90/87%); for 436, stroke of unknown type (29/29%; 19/16%); and for 435, TIA (75/82%; 80/78%). The SISR database has a high PPV; sensitivity is high for TIA, but low for specific stroke ICD codes.