Conversion Rate of Tuberculin Skin Test among Medical Students in Songklanagarind Hospital

Sarinpant Pongpant, Chanon Kongkamol

Abstract


OBJECTIVE:
Airborne and Tuberculosis (TB) control measures have been implemented in Songklanagarind hospital. The infection control unit of the hospital has provided a voluntary two-step tuberculin skin test (TST) for pre-clinical medical students and serial TST for clinical medical students. This study aimed to determine the incidence of negative outcome and booster phenomenon from two-step TST as well as the TST conversion rate from serial TST among medical students in the hospital.

MATERIALS AND METHODS:
Percentages of negative cases and boosting phenomenon were calculated from the two-step TST records. Conversion rates of each year were calculated from serial TST data. Then the TST conversion rates were predicted based on the Jointpoint model.

RESULTS:
Two-step TSTs performed from 2001 to 2016 showed 40 to 100% of negative cases and zero to 14% of boosting phenomenon among 2,271 medical students. Serial TSTs from 2002 to 2016 among 665 medical students showed 60 conversion cases. Conversion rates varied from zero to 13.6%. The decline of conversion rates after the year 2006 is demonstrated in 1-Joinpoint model with statistical significance (p = 0.0129). The model corresponded with the timeline data of airborne infection control measures which were mostly implemented after 2006.

CONCLUSIONS:
A decline in TST conversion rate was shown after 2006. This coincided with airborne infection control measures at the institute.

Keywords:
tuberculin skin test, conversion rate, medical student, Songklanagarind hospital

Address Correspondence to author:
Sarinpant Pongpant, MD. Occupational health unit, Department of family medicine and preventive medicine, Faculty of Medicine, Prince of Songkla University, Songkhla, 90110, Thailand. email: jibpongpant@gmail.com

Received: May 25, 2018
Revision received: May 31, 2018
Accepted after revision: July 3, 2018
BKK Med J 2018;14(2): 17-21.

DOI: 10.31524/bkkmedj.2018.09.004

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