Does clinical evidence support ICD-9-CM diagnosis coding of complications?
BACKGROUND
Hospital discharge diagnoses, coded by use of the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM), increasingly determine reimbursement and support quality monitoring. Prior studies of coding validity have investigated whether coding guidelines were met, not whether the clinical condition was actually present.


OBJECTIVE
To determine whether clinical evidence in medical records confirms selected ICD-9-CM discharge diagnoses coded by hospitals.


METHODS
Retrospective record review of 485 randomly sampled 1994 hospitalizations of elderly Medicare beneficiaries in Califomia and Connecticut.


METHODS
Proportion of patients with specified ICD-9-CM codes representing potential complications who had clinical evidence confirming the coded condition.


RESULTS
Clinical evidence supported most postoperative acute myocardial infarction diagnoses, but fewer than 60% of other diagnoses had confirmatory clinical evidence by explicit clinical criteria; 30% of medical and 19% of surgical patients lacked objective confirmatory evidence in the medical record. Across 11 surgical and 2 medical complications, objective clinical criteria or physicians' notes supported the coded diagnosis in >90% of patients for 2 complications, 80% to 90% of patients for 4 complications, 70% to <80% of patients for 5 complications, and <70% for 2 complications. For some complications (postoperative pneumonia, aspiration pneumonia, and hemorrhage or hematoma), a large fraction of patients had only a physician's note reporting the complication.


CONCLUSIONS
Our findings raise questions about whether the clinical conditions represented by ICD-9-CM codes used by the Complications Screening Program were in fact always present. These findings highlight concerns about the clinical validity of using ICD-9-CM codes for quality monitoring.
Department of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center, the Charles A Dana Research Institute, Boston, Massachusetts 02215, USA. Ellen_Mccarthy@caregroup.harvard.edu
E P
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McCarthy
L I
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Iezzoni
R B
RB
Davis
R H
RH
Palmer
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Cahalane
M B
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Hamel
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Mukamal
R S
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Phillips
D T
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Davies
D000368:Aged; D002140:California; D003237:Connecticut; D004194:Disease / Q000145:classification; D017052:Hospital Mortality; D006801:Humans; D007049:Iatrogenic Disease; D007902:Length of Stay; D008485:Medical Audit / Q000379:methods*; D008499:Medical Records / Q000145:classification*; D006278:Medicare; D010351:Patient Discharge; D011183:Postoperative Complications / Q000145:classification* / Q000401:mortality; D011366:Professional Review Organizations; D019984:Quality Indicators, Health Care; D011897:Random Allocation; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013530:Surgical Wound Infection / Q000145:classification / Q000401:mortality; D014481:United States