Sexually Transmitted Diseases, June 2007, Vol. 34, No. 6, p.389-391 DOI: 10.1097/01.olq.0000245916.45429.ec Copyright © 2007, American Sexually Transmitted Diseases Association All rights reserved. Note Reliability and Criterion-Related Validity of Self-Report of Syphilis DENNIS G. FISHER, PHD,* GRACE L. REYNOLDS, DPA,* BETH CREEKMUR, BA,* MARK E. JOHNSON, PHD,t AND NETTI DEAUGUSTINE, BA$ Objective: To determine the test-retest reliability, sensitivity and specificity, and criterion-related validity of the Risk Behavior Assess- ment (RBA) syphilis questions. The RBA is a standardized instrument that has been used in several studies of STDs in drug users. Methods: For the test-retest reliability study, 219 injection drug users completed the RBA twice within a 48-hour period. To determine criterion-related validity, 207 individuals, who also completed the RBA, were tested with the rapid plasma reagin test (RPR), and 206 individuals were also tested with the Serodia Treponema pallidum particle agglutination test (TP-PA). Results: The test-retest reliability for the question "How many times have you been told by a doctor or a nurse that you had syphilis?" was 0.78. The test-retest reliability for the question "In what year were you last treated for syphilis?" was 0.89. For the comparison of self- report with the RPR test, the sensitivity of self-report was 46.2% and the specificity was 95.7%. For the comparison of self-report with the TP-PA test, the sensitivity of self-report was 37% and the specificity was 97.7%. Conclusions: Self-reports of syphilis infection history were found to have good reliability, excellent specificity, and moderate sensitivity. These characteristics need to be taken into account in any study using these self-report items. AS A RESULT OF THE HIGH costs of laboratory tests, self- report is often the only measure used in research regarding sexu- ally transmitted diseases (STDs). Using self-report of disease status without considering the data's reliability and validity can seriously compromise the value of any research findings. There- fore, reliability and validity of disease self-report status is impor- tant. This article reports on the reliability and criterion-related validity of self-report of syphilis. The syphilis questions are from the Risk Behavior Assessment (RBA; National Institute on Drug Abuse),' a standardized instrument used in several studies of STDs in drug users.'- -7 The RBA measures sexual and drug-risk behaviors, demographics, and history of previous diagnosis This research was supported in part by contract number H-700939- 1 from the County of Los Angeles, Office of AIDS Programs and Policy. Further support was provided in part by contract 28569 from the City of Long Beach, California, Department of Health. Correspondence: Dennis G. Fisher, PhD, Center for Behavioral Research and Services, 1090 Atlantic Avenue, Long Beach, CA 90813. E-mail: dfisher@csulb.edu. Received for publication March 11, 2006, and accepted August 14, 2006. From the *Center for Behavioral Research and Services, California State University, Long Beach, California; tBehavioral Health Research and Services, University of Alaska, Anchorage, Alaska; and the Department of Health and Human Services, City of Long Beach, Long Beach, California with selected infectious diseases, including syphilis. Most of the items have good test—retest reliability and recent drug use has good validity. 8-03 In 2 separate studies, we determined the test—retest reliabil- ity, 31112 sensitivity and specificity, and criterion-related validity of the RBA syphilis items. Reliability or stability of a measure is an essential precursor in describing properties of a measure. Sen- sitivity and specificity can be used to express criterion-related validity when the criterion (or gold standard) takes only 2 values such as positive versus negative laboratory test results.' 3 In our study, we compared self-report data and biomarkers as revealed by both the ASI Rapid Plasma Reagin Card Test" and the Serodia TP-PA qualitative gelatin particle agglutination assay. 15-17 Once a participant has had syphilis, the Serodia assay (TP-PA) will remain reactive for life.' 5 In study 1, to determine test—retest reliability, we recruited out-of-treatment injection drug users from the national NIDA Cooperative Agreement (CA). The data collection took place dur- ing March 1992. The 11 sites participating were Anchorage, Alas- ka; Denver, Colorado; Detroit, Michigan; Houston, Texas; Long Beach, California; Miami, Florida; New York, NY; Philadelphia, Pennsylvania; Portland, Oregon; San Francisco, California; and Tucson, Arizona. The sample consisted of 219 participants. Eligi- bility for inclusion was being at least 18 years old, not intoxicated or mentally impaired, self-reported injection drug or crack cocaine use within the last 30 days, visible signs of injection drug use (i.e., track marks), and/or positive ONTRAK' 8 '° urinalysis confirming morphine or cocaine metabolites and no enrollment in a drug treatment program within the last 30 days. Table 1 provides participants' demographic information for study 1. These partici- pants completed the RBA twice within a 48-hour period. The 48-hour time period was originally chosen for the comparison of self-report of recent drug use with urine test data reported else- where.'• The specific questions analyzed in this study are: "How many times have you been told by a doctor or a nurse that you had syphilis?" and "In what year were you last treated?" 389