Inaccuracy such as weekday admissions of false-positive cases with low case fatality
THURSDAY, May 19, 2016 (HealthDay News) — Inaccurate coding can introduce biases in studies based on administrative data, according to research published online May 16 in The BMJ.
Linxin Li, and Peter M. Rothwell, M.D., Ph.D., from the University of Oxford in the United Kingdom, examined the accuracy of coding of admissions for stroke among patients with clinically confirmed acute stroke in nine general practices in Oxfordshire (the Oxford Vascular Study [OXVASC]).
The researchers ascertained 2,373 episodes of acute stroke among a study population of 92,728. Of the 319 strokes missed by coding, there was no bias in distribution of weekend versus weekday admission. Of the 1,693 admissions for stroke identified by coding, after case adjudication, 62.3 percent were confirmed to be acute stroke. Among the 638 false-positive coded cases, patients were more likely to be admitted on weekdays (41.0 percent) than weekends (26.5 percent) (P < 0.001); this was partially due to weekday elective admissions after previous stroke being miscoded as new stroke episodes. The 30-day case fatality was lower after these elective admissions versus confirmed acute stroke admissions (P < 0.001). There was a difference in the relative 30-day case fatality for weekend versus weekday admissions between correctly coded acute stroke admission and false-positive coding cases (P < 0.001).
“Any conclusion based on administrative data alone should be interpreted with caution,” the authors write.
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