P3-S1.39 Comparison of strategies for empiricChlamydia trachomatis(CT) treatment in the Denver Metro Health Clinic: treat MPC vs increased WBC on wet prep
Authors: Peterson K , Mickiewicz T 
Published: July 2011

Background

Our STD stat lab reports WBC on the vaginal wet prep as normal or increased (≥10 WBC/LPF). WBC reflect inflammation and may be associated with CT infection. Mucopurulent cervicitis (MPC) may also result from CT, and is diagnosed by visualising the cervix on speculum exam. We modelled what effect two strategies would have on empiric CT treatment in the Denver Metro Health Clinic (DMHC). Current strategy is to treat all MPC to cover possible CT. We compared that to expected results if all increased WBC on wet prep were treated to cover possible CT. Early treatment is thought to be important in preventing complications in women. The US Infertility Prevention Project guidelines call for treating 75% of women by 14 days after testing, and 90% by 30 days.

Methods

The DMHC is an urban STD clinic with an electronic medical record (EMR). The EMR was used to identify all women attending the DMHC and receiving a wet prep between 09/01/06 and 02/04/11. They were divided into two groups by wet prep results (increased WBC vs normal WBC) and further divided by diagnoses of MPC and CT. Differences between the groups were assessed by χ2, and the sensitivity and specificity of increased WBC and MPC for CT were calculated. For each strategy, the % of treated and missed cases of CT; % of missed cases that would have been treated by the other strategy; % of treated patients without CT; and the number of CT-negative patients treated, and CT-positive patients missed, for every CT case treated were calculated. NGU in men was used as a comparison where applicable. For CT cases that were missed by the MPC strategy, actual time to treatment was identified.

Results

19 027 women were seen during this time and 12 066 had a wet prep done. Of these, 5985 had increased WBC, 6081 had normal WBC, 900 had MPC and 1628 had CT. CT was positive in 1089 with increased WBC (182 had MPC) and 539 with normal WBC (27 had MPC). Both MPC and increased WBC were significantly associated with CT infection (p<0.0001): CT positivity rates were 23.2% in women with MPC; 18.2% in women with increased WBC; and 8.7% in women with neither. The sensitivity and specificity of MPC for CT were 12.8% and 93.3% and for increased WBC 66.9% and 53.1%. See Abstract P3-S1.39 table 1 for comparison of the strategies.

Abstract P3-S1.39 Table 1

Comparison of empiric treatment strategies using MPC or increased WBC on wet prep to direct treatment

Strategy% (N) CT cases treated% (N) CT cases missed% (N) missed CT cases other strategy covers% (N) treated patients without CTCT-negative patients treated/CT case treatedCT-positive cases missed/CT case treatedTime to treatment for missed CT cases in % Note: 0 days = treated as contact day of visitTreat all MPC as CT13% (209)87% (1419)64% (907)77% (691)3.36.80 days: 32%1–14 days: 29%15–30 days: 11%31–90 days: 5%Not treated: 23%Treat all increased WBC as CT67% (1089)33% (539)5% (27)82% (4896)4.50.5–Treat all NGU as CT(1725)––64% (3105)1.8––

Conclusions

Increased WBC have poor specificity for CT but better sensitivity than MPC. Given greater delay in treatment with the MPC strategy, the increased WBC strategy is attractive for our clinic.