detection of ASCUS and LSIL. Although agreement between SC and CC samples was also only moderate for those with HR and LR types, there is no gold standard by which to determine which collection method is more accurate. Future studies will help to define this gold standard and clarify the role of HPV DNA self-testing in screening and management of adolescents. ECONOMIC ANALYSIS OF CHLAMYDIA SCREENING STRATEGIES FOR MALE YOUTH ENTERING THE JOB CORPS Diane R. Blake, M.D., Thomas C. Quinn, M.D., and Charlotte A. Gaydos, Dr.P.H. Dept of Pediatrics, University of Massachusetts Medical School, Worcester, MA; and Dept of Medicine, Johns Hopkins School of Medicine, Baltimore, MD. Background: Since Chlamydia trachomatis infections are most often asymptomatic, many infected male youth are unaware of their infection. Untreated infections can lead to serious and costly sequelae, particularly for female partners of infected males. Objective: To determine the most cost-effective chlamydia screen- ing strategy for male youth entering the Job Corps. Methods: Setting: Massachusetts Job Corps site. Participants: 16 –24 year old male youth entering Job Corps between 1/01 and 7/03. Primary Outcome Measure: Chlamydia infection as defined by a positive urine based nucleic acid amplification test (NAAT). Analysis: A decision analysis was modeled for a hypothetical cohort of 2000/year of 16 –24 year old male youth entering New England Job Corps sites. Incremental cost-effectiveness of 3 strat- egies was compared: 1) Current standard: Universal screening for chlamydia with a urine based NAAT, 2) Selective NAAT screen- ing of males who have a positive urine leukocyte esterase (LE) test, and 3) No screening. The model incorporated programmatic costs of screening and treatment and medical cost savings from se- quelae prevented in infected males and female partners. The analysis was conducted from the health care system perspective. All costs were adjusted to 2003 dollars and future costs discounted at a rate of 3%. Results: Chlamydia prevalence in the sampled population of 354 young men was 8.3%, and the average number of female sexual partners/infected male was 1.5. Fifty-six percent of males infected with chlamydia were positive by LE. For the hypothetical cohort, selective NAAT screening of those with a positive LE prevented 42 cases of PID and 4 cases of epididymitis, saving $55,000 compared with no screening. Universal NAAT screening prevented an additional 35 cases of PID in females and 3 cases of epididymitis in males, saving an additional $38,000. Universal screening re- mained the most cost saving strategy for prevalences of 2.7% and higher. In two-way sensitivity analyses, as prevalence declined, the model became sensitive to the cost of the NAAT and the costs of treating PID sequelae. Conclusions: The Job Corps is currently using the most cost- effective strategy for screening incoming male youth for chla- mydia. Savings are due primarily to the prevention of PID in recent and future partners of index males. Screening Job Corps male entrants using a nucleic acid amplification test provides a public health opportunity to substantially reduce chlamydia infections among youth at risk for sexually transmitted dis- eases. BONE MARKERS IN ADOLESCENT GIRLS ON DEPOT MEDROXYPROGESTERONE ACETATE AND ULTRA-LOW- DOSE ORAL CONTRACEPTIVES Ellen S. Rome, M.D., M.P.H., Michelle Secic, M.S., Julie Ziegler, M.A., Rina Lazebnik, M.D., Andrea Bonny, M.D., Peggy Stager, M.D., Ray Harvey, B.S., and Barbara A. Cromer, M.D. The Children’s Hospital at the Cleveland Clinic, MetroHealth Medical Center, Rainbow Babies and Childrens Hospital, Case Western Reserve University School of Medicine, Cleveland, OH. Background: Bone markers including bone specific alkaline phos- phatase (BSAP) and deoxypyridinoline (DPD) reflect bone forma- tion and resorption, respectively. Therefore, examination of bone markers may be helpful in explaining changes in bone metabolism associated with hormonal contraception in adolescents. Objectives: The purpose of this study was to examine bone markers in adolescent girls on depot medroxyprogesterone acetate (DMPA) as compared with bone markers in girls using ultra-low- dose oral contraceptives (20 ucg OC) and girls receiving no treatment (controls). Methods: A prospective, observational design was used to com- pare bone biomarkers (BSAP in U/L and DPD in nmol/mmol Cr) at baseline and 12 months among girls ages 12–18 years starting DMPA (n = 53), a 20 ucg OC (n = 165), or no hormone treatment (n = 152). Repeated measures analysis of variance techniques were used to examine the relationship of each biomarker to demographic factors (age, race, weight) and treatment over time. The natural log transformation was used to normalize the distri- bution of biomarkers. Back transformations were computed for reporting purposes. Results: The mean age of all girls was 15.5 years (1.5 SD) with controls significantly younger than the two treatment groups (.01). BSAP levels, adjusted for race, age, weight and time, were 40.4 U/L (1.03 SE) for controls, 35.2 U/L(1.05 SE) for the DMPA group, and 35.5 U/L (1.03 SE) for the OC group (p  .05 for control versus DMPA and OC groups). DPD levels, with the same adjustments, were 9.9 nmol/mmol Cr (1.03 SE) for con- trols, 9.1 (1.05 SE) for the DMPA group, and 8.9 (1.03 SE) for the OC group (p = 0.06 for control versus DMPA and OC groups). Conclusions: Over the course of the year, there was evidence of increased bone turnover, e.g., both formation and resorption, in adolescent girls not receiving hormone treatment versus those on hormonal contraception. This finding may indicate a suppression of bone metabolism in girls receiving either DMPA or ultra-low dose oral contraceptives. THE CHANGING EPIDEMIOLOGY OF PERTUSSIS: SHOULD WE ADOPT A VACCINE POLICY FOR ADOLESCENTS? Lawrence J. D’Angelo, M.D., M.P.H. and Manya D. Magnus, Ph.D. Division of Adolescent and Young Adult Medicine, Children’s National Medical Center, Departments of Pediatrics, School of Medicine and Department of Epidemiology, School of Public Health and Health Services, George Washington University, Washington, DC. Purpose: Despite the remarkable success in reducing the number of cases of pertussis nationally since the introduction of a vaccine in the mid 1940’s, this disease remains a major source of morbidity in the United States. Recent epidemiological trends have shown an increase in the total number of cases, and a distinct shift in the age distribution of these cases. Simultaneously, a vaccine has become February 2004 RESEARCH PRESENTATIONS 119