Accuracy of the ICD-9 codes for identifying TIA and stroke in an Italian automated database

Neurol Sci (2004) 25:281288DOI 10.1007/s10072-004-0355-8ORIGINALM.A. Leone A. Capponi C. Varrasi R. Tarletti F. MonacoAccuracy of the ICD-9 codes for identifying TIA and stroke

in an Italian automated databaseReceived: 14 June 2004 / Accepted in revised form: 12 November 2004Abstract 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

430438 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

430438: 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.Key words TIA Stroke ICD codes Discharge

Accuracy Sensitivity Positive predictive valueIntroductionThe use of administrative databases for evaluating the quality of care for stroke patients is still uncommon [14]. The

feasibility of studies relying on such databases mostly

depends on the validity and reliability of the data recorded.

Few studies have evaluated the validity of databases using

the International Classification of Diseases, 9th revision

(ICD-9) codes in stroke patients by comparing the information from recorded discharge diagnoses with medical charts.

Sensitivity is generally high [49], but positive predictive

value (PPV) depends on the inclusion of first-ever or recurrent strokes, single codes evaluated or whether codes in the

primary or secondary position are considered. We aimed to

evaluate sensitivity and PPV of the ICD-9 codes for identifying cases of transient ischaemic attack (TIA) and stroke in

the Sistema Informativo Sanitario Regionale (SISR), a health

care automated database of the Piedmont Region, NW Italy.

The SISR was created in 1976...