Validity of Diagnostic Codes for Acute Stroke in Administrative Databases: A Systematic Review

Abstract

ObjectiveTo conduct a systematic review of studies reporting on the validity of International Classification of Diseases (ICD) codes for identifying stroke in administrative data.MethodsMEDLINE and EMBASE were searched (inception to February 2015) for studies: (a) Using administrative data to identify stroke; or (b) Evaluating the validity of stroke codes in administrative data; and (c) Reporting validation statistics (sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), or Kappa scores) for stroke, or data sufficient for their calculation. Additional articles were located by hand search (up to February 2015) of original papers. Studies solely evaluating codes for transient ischaemic attack were excluded. Data were extracted by two independent reviewers; article quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies tool.ResultsSeventy-seven studies published from 1976–2015 were included. The sensitivity of ICD-9 430-438/ICD-10 I60-I69 for any cerebrovascular disease was ≥ 82% in most [≥ 50%] studies, and specificity and NPV were both ≥ 95%. The PPV of these codes for any cerebrovascular disease was ≥ 81% in most studies, while the PPV specifically for acute stroke was ≤ 68%. In at least 50% of studies, PPVs were ≥ 93% for subarachnoid haemorrhage (ICD-9 430/ICD-10 I60), 89% for intracerebral haemorrhage (ICD-9 431/ICD-10 I61), and 82% for ischaemic stroke (ICD-9 434/ICD-10 I63 or ICD-9 434&436). For in-hospital deaths, sensitivity was 55%. For cerebrovascular disease or acute stroke as a cause-of-death on death certificates, sensitivity was ≤ 71% in most studies while PPV was ≥ 87%.ConclusionsWhile most cases of prevalent cerebrovascular disease can be detected using 430-438/I60-I69 collectively, acute stroke must be defined using more specific codes. Most in-hospital deaths and death certificates with stroke as a cause-of-death correspond to true stroke deaths. Linking vital statistics and hospitalization data may improve the ascertainment of fatal stroke.

Differentiating Incident from Recurrent Stroke Using Administrative Data: The Impact of Varying Lengths of Look-Back Periods on the Risk of Misclassification

“…Where the first recorded stroke diagnosis in each admission was ICD-10 code I64, “stroke, not otherwise specified as haemorrhage or infarction,” subsequent episodes of care recording a specific stroke diagnosis were interrogated to inform the sub-type; otherwise, I64 coded strokes were considered ischaemic strokes, as evidence in Australia indicates that these cases rarely represent haemorrhagic cerebrovascular events (1%) or transient ischaemic attacks (2%) [20,21]. This approach is recommended in 2 recent systematic reviews of stroke coding validity to increase the sensitivity of ischaemic stroke sub-typing without compromising the PPV [22,23]. …”

Protocol for validating cardiovascular and cerebrovascular ICD-9-CM codes in healthcare administrative databases: the Umbria Data Value Project

“…Expected accuracy figures were based on the published literature. [6][7][8][9] Sensitivity and specificity will be analysed separately for each ICD-9-CM code by constructing 2×2 tables. Sensitivity expresses the proportion of 'true positives' (ie, AMI classified as positive by the administrative database and medical record review) and all cases deemed positive by medical chart review.…”

“…5 However, there is a concern that the power of administrative databases as a source of healthcare information cannot be fully exploited unless they are thoroughly validated. [6][7][8][9] For instance, a systematic review 10 of ICD-9 code validation in Italian administrative databases reported that only a few regional databases have been validated, and just for a limited number of ICD-9 codes of diseases. [11][12][13][14][15][16][17][18] While non-clinical information in healthcare databases, such as demographic and prescription data, are highly accurate, 19 20 reliability of registered diagnoses and procedures is variable.…”

Risk of stroke and bleeding in patients with heart failure and chronic kidney disease: a nationwide cohort study

“…We cannot rule out that some patients might have had undiagnosed AF, because (any) heart disease is associated with an increased risk of developing AF; however, censoring for a diagnosis of AF during follow‐up did not change our main conclusions. The diagnosis of ischaemic stroke has also been validated and found to have a positive predictive value of 80–90% 13, 34. We included unspecified stroke in the definition of ischaemic stroke, as many such strokes are of ischaemic origin 13.…”