Validity of diagnostic codes and prevalence of psoriasis and psoriatic arthritis in a managed care population, 1996-2009

UMMS Affiliation

Meyers Primary Care Institute; Department of Medicine, Division of Rheumatology; Department of Orthopedics and Physical Rehabilitation

Publication Date


Document Type



Psoriasis; Arthritis, Psoriatic; Prevalence


Clinical Epidemiology | Dermatology | Health Services Research | Pharmacy and Pharmaceutical Sciences | Rheumatology | Skin and Connective Tissue Diseases


BACKGROUND: Few population-based studies have reported the prevalence of psoriatic disease.

OBJECTIVE: We validated computerized diagnoses to estimate the prevalence of psoriasis and psoriatic arthritis.

METHOD: We identified adults with >/=1 ICD-9 diagnosis codes of 696.0 (psoriatic arthritis) or 696.1 (psoriasis) in clinical encounter data during 1996-2009 and used chart review to confirm the diagnoses in random samples of patients. We then used the best performing case-finding algorithms to estimate the point prevalence of psoriasis and psoriatic arthritis.

RESULTS: The number of persons with a diagnosis for psoriasis (ICD-9 code 696.1) was 87 827. Chart review of a random sample of 101 cases with at least one dermatologist-rendered psoriasis code revealed a positive predictive value (PPV) of 90% (95% CI, 83-95) with sensitivity of 88% (95% CI, 80-93). Psoriatic arthritis (code 696.0) was recorded for 5187 patients, with the best performing algorithm requiring >/=2 diagnoses recorded by a rheumatologist or >/=1 diagnosis recorded by a rheumatologist together with >/=1 psoriasis diagnoses recorded by a dermatologist; the PPV was 80% (95% CI, 70-88) with sensitivity 73% (95% CI, 63-82). Among KPNC adults, the point prevalence of psoriasis, with or without psoriatic arthritis, was 939 (95% CI, 765-1142) per 100 000, and the overall prevalence of psoriatic arthritis, with or without psoriasis, was 68 (95% CI, 54-84) per 100 000.

CONCLUSION: Within an integrated health care delivery system, the use of computerized diagnoses rendered by relevant disease specialists is a valid method for identifying individuals with psoriatic disease.

Copyright (c) 2013 John Wiley and Sons, Ltd.


Computerized medical information, Epidemiology, Incidence, Prevalence, Health maintenance organizations, Pharmacoepidemiology, Psoriasis, Psoriatic arthritis

DOI of Published Version



Asgari MM, Wu JJ, Gelfand JM, Salman C, Curtis JR, Harrold LR, Herrinton LJ. Validity of diagnostic codes and prevalence of psoriasis and psoriatic arthritis in a managed care population, 1996-2009. Pharmacoepidemiol Drug Saf. 2013 Aug;22(8):842-9. doi: 10.1002/pds.3447. Link to article on publisher's site

Journal/Book/Conference Title

Pharmacoepidemiology and drug safety

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Link to Article in PubMed

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