PT  - JOURNAL ARTICLE
AU  - HIROE SATO
AU  - NAOHITO TANABE
AU  - AKIRA MURASAWA
AU  - YASUHIRO OTAKI
AU  - TAKEHITO SAKAI
AU  - TOSHIAKI SUGAYA
AU  - SATOSHI ITO
AU  - HIROSHI OTANI
AU  - ASAMI ABE
AU  - HAJIME ISHIKAWA
AU  - KIYOSHI NAKAZONO
AU  - TAKESHI KURODA
AU  - MASAAKI NAKANO
AU  - ICHIEI NARITA
TI  - Procalcitonin Is a Specific Marker for Detecting Bacterial Infection in Patients with Rheumatoid Arthritis
AID  - 10.3899/jrheum.111601
DP  - 2012 Aug 01
TA  - The Journal of Rheumatology
PG  - 1517--1523
VI  - 39
IP  - 8
4099  - http://www.jrheum.org/content/39/8/1517.short
4100  - http://www.jrheum.org/content/39/8/1517.full
SO  - J Rheumatol2012 Aug 01; 39
AB  - Objective. Rheumatoid arthritis (RA) is a chronic inflammatory disease accompanied by many complications, and serious infections are associated with many of the advanced therapeutics used to treat it. We assessed serum procalcitonin (PCT) levels to distinguish bacterial infection from other complications in patients with RA. Methods. One hundred eighteen patients experiencing an RA flare, noninfectious complication of RA or its treatment, nonbacterial infection, or bacterial infection were studied. Serum PCT concentrations were determined with a chemiluminescent enzyme immunoassay. Results. All patients experiencing an RA flare showed negative PCT levels (≤ 0.1 ng/ml; n = 18). The PCT level was higher in the bacterial infection group (25.8% had levels ≥ 0.5 ng/ml) than in the other 3 groups (0.0–4.3% had levels ≥ 0.5 ng/ml) and the difference was significant among groups (p = 0.003). Conversely, no statistically significant difference was observed among the groups with C-reactive protein (CRP) concentration ≥ 0.3 mg/dl (p = 0.513), white blood cell (WBC) count > 8500/mm3 (p = 0.053), or erythrocyte sedimentation rate (ESR) > 15 mm/h (p = 0.328). The OR of high PCT level (≥ 0.5 ng/ml) for detection of bacterial infection was 19.13 (95% CI 2.44–149.78, p = 0.005). Specificity and positive likelihood ratio of PCT ≥ 0.5 ng/ml were highest (98.2% and 14.33, respectively) for detection of bacterial infection, although the sensitivity was low (25.8%). Conclusion. Serum PCT level is a more specific marker for detection of bacterial infection than either CRP, ESR, or WBC count in patients with RA. High PCT levels (≥ 0.5 ng/ml) strongly suggest bacterial infection. However, PCT < 0.5 ng/ml, even if < 0.2 ng/ml, does not rule out bacterial infection and physicians should treat appropriately.