Fig 1.
International Classification of Diseases (ICD) codes for cerebrovascular disease.
* 433: occlusion/stenosis of pre-cerebral arteries with or without infarction. † 434: thrombosis/embolism of cerebral arteries with or without infarction. Codes in blue text denote ICD-9 codes which most closely represent stroke when subdivided using additional coding available in the clinically modified version of ICD-9 (ICD-9-CM) used in North America. In ICD-9-CM, ‘with infarction’ (433.x1, 434.x1) is distinguished from ‘without infarction’ (433.x0, 434.x0).
‡ 436: acute, ill-defined cerebrovascular disease
¶ a pathological term for ischaemic stroke
§ G46: not a diagnostic code; may be used for the presenting symptoms of either stroke or TIA.
Fig 2.
*Additional studies identified from bibliography screening. †Additional studies identified from review articles and bibliography screening.
Table 1.
Effect on PPV of codes used to identify stroke: within-study comparisons*.
Table 2.
Effect on PPV of codes used to identify ischaemic stroke: within-study comparisons*.
Fig 3.
Positive predictive values of codes for stroke.
H: hospital data, D: death certificates, H+D: hospital data and death certificates; x = number of coded events confirmed as ‘true cases’ by the reference standard; y = total number of coded events; x/y = PPV. Circles represent PPVs, and horizontal lines denote 95% confidence intervals (CIs). Circle size is proportional to the inverse variance of the PPV. Where more than one result was available for a particular study, the result for the largest number of coded events validated is shown.
* Cerebrovascular codes: I60-I69+/-G45 (ICD-10) or 430–438 (ICD-9), unless otherwise specified
† Mean PPV (taken from the range published in the study)
‡ Excluding codes 435 (TIA) and 438 (sequelae of cebrovascular disease)
§ Excluding code 435 (TIA) and including code 342 (hemiplegia and hemiparesis)
¶ Excluding code 435 (TIA)
# Stroke-specific codes: 160, 161, 163, 164 (ICD-10), 430, 431, 434, 436 (ICD-9), 430, 431, 433.x1, 434.x1 (ICD-9-CM).
¥ Ischaemic stoke and unspecified stroke codes: I63, I64 (ICD-10), 434, 436 (ICD-9), 433.x1, 434.x1, 436 (ICD-9-CM)
**Ischaemic stroke codes:163 (ICD-10), 434 (ICD-9), 433.x1, 434.x1 (ICD-9-CM)
†† Haemorrhagic stroke codes:I60, I61 (ICD-10), 430, 431 (ICD-9)
‡‡ Subarachnoid haemorrhage stroke codes:I60 (ICD-10), 430 (ICD-9)
¶¶ Intracerebral haemorrhage stroke codes:I61 (ICD-10), 431 (ICD-9)
Fig 4.
Positive predictive values of codes for ischaemic stroke.
H: hospital data, D: death certificates, H+D: hospital data and death certificates; x = number of coded events confirmed as ‘true cases’ by the reference standard; y = total number of coded events; x/y = PPV. Circles represent PPVs, and horizontal lines denote 95% confidence intervals (CIs). Circle size is proportional to the inverse variance of the PPV. Where more than one result was available for a particular study, the result for the largest number of coded events validated is shown.
† Mean PPV (taken from the range published in the study)
¥ Ischaemic stoke and unspecified stroke codes: I63, I64 (ICD-10), 434, 436 (ICD-9), 433.x1, 434.x1, 436 (ICD-9-CM)
**Ischaemic stroke codes:163 (ICD-10), 434 (ICD-9), 433.x1, 434.x1 (ICD-9-CM)
Fig 5.
Positive predictive values of codes for haemorrhagic stroke.
H: hospital data, D: death certificates, H+D: hospital data and death certificates; x = number of coded events confirmed as ‘true cases’ by the reference standard; y = total number of coded events; x/y = PPV. Circles represent PPVs, and horizontal lines denote 95% confidence intervals (CIs). Circle size is proportional to the inverse variance of the PPV. Where more than one result was available for a particular study, the result for the largest number of coded events validated is shown.
† Mean PPV (taken from the range published in the study)
†† Haemorrhagic stroke codes:I60, I61 (ICD-10), 430, 431 (ICD-9)
‡‡ Subarachnoid haemorrhage stroke codes:I60 (ICD-10), 430 (ICD-9)
¶¶ Intracerebral haemorrhage stroke codes:I61 (ICD-10), 431 (ICD-9)