A Comparison of the Military Entrance Processing Station Screening Audiogram with the Defense Occupational and Environmental Health Readiness System Reference Audiogram at Fort Sill, Oklahoma, in 2000

Military Medicine, Feb 2006 by Niebuhr, David W, Completo, John D, Helfer, Thomas M, Chandler, David W

Background: The Department of Defense Hearing Conservation Program requires that a reference audiogram be performed at initial entry training (IET), before noise exposure. In the Army, only Fort Sill, home of the field artillery, and Fort Benning, home of the infantry, are in compliance. All military applicants receive a screening audiogram at a military entrance processing station (MEPS) to qualify for service. This audiogram does not meet the Defense Occupational and Environmental Health Readiness System-Hearing Conservation (DOEHRS-HC) standard. Nevertheless, it has been proposed that the MEPS screen be used as the reference because of limited resources and time during IET medical in-processing. Methods: A total of 11,816 individual reference audiograms performed at Fort Sill 95th Adjutant General Recruit Reception Center in 2000 were identified in the DOEHRS-HC database. Results of the MEPS screening audiograms were found for 11,311 (96%) of these individuals. The two audiograms were compared by frequency and ear and by using the two Department of Defense criteria for threshold shift. Results: A total of 14.49% (95% confidence interval, 14.48-14.50%) of audiograms using the three-frequency average difference and 23.19% (95% confidence interval, 23.18-23.20%) using the four-frequency difference in either ear demonstrated a threshold shift. The mean difference in intensity between the two audiograms ranged from 5 to 12 dB and varied by frequency and ear, with the greatest differences being seen at 500 and 6,000 kHz and in the left ear, compared with the right ear. The mean threshold level was higher for each frequency in the DOEHRS-HC audiogram, compared with the MEPS audiogram. Conclusions: Approximately 15% of soldiers at Fort Sill in 2000 showed a clinically significant threshold difference between their MEPS screening and the DOEHRS-HC baseline audiogram. Methodological variations in testing and interval noise-induced hearing loss could account for these differences. The results do not support the use of the MEPS screening audiogram as the reference audiogram. Compliance with the Hearing Conservation Program in the Army would require either improving MEPS testing to DOEHRS-HC standards or performing baseline audiograms at all five IET sites.

Introduction

In calendar year 2000, the U.S. Military Entrance Processing 1 Command (USMEPCOM) received >365,000 active military applications at 65 stations worldwide; > 188,000 personnel accessed into the active component military, and ~ 159,000 additional personnel accessed into the selected reserve component.1 Part of the accession physical examination is a hearing screening audiogram. Hearing tests involve presenting to an individual pure tone sounds at various frequency levels and determining the minimal threshold (in decibels) that can be detected. Department of Defense (DoD) Instruction 6130.3 sets the acceptable audiometric hearing levels in both ears as follows: (1) pure tone levels at 500, 1,000, and 2,000 Hz of not more than 30 dB on average, with no individual level of >35 dB at those frequencies; and (2) pure tone levels of not more than 45 dB at 3,000 Hz and 55 dB at 4,000 Hz.2

Military applicants range in age from 17 to 35 years, with >90% being 2,060 in 2001.3 The Accession Medical Standards Analysis and Research Activity (AMSARA) has studied the military retention patterns of recruits with a waiver for hearing loss. Results varied by service, but in the Army and Navy accessions with a hearing loss waiver had a lower likelihood of retention than did matched nonwaived accessions.3 The accuracy of preinduction audiograms performed at a military entrance processing station (MEPS) was evaluated by Chandler et al.4

The DoD Hearing Conservation Program is detailed in DoD Instruction 6055.12.5 It recognizes that initial entry training (IET) is a noise-hazardous environment, and it requires that a reference audiogram be performed for all military personnel at basic training, before noise exposure. The prevalence of noiseinduced hearing threshold shift is estimated to be 15.5% (95% confidence interval [CI[, 13.3-17.6) in the United States for 12to 19-year-old individuals, based on Third National Health and Nutrition Examination Survey data.6 The prevalence of hearing loss among soldiers with

MEPS screening audiograms were obtained by using Tremetrics RA400 microprocessor audiometers (Benson Medical Instrument, Minneapolis, Minnesota) with either automated or manual transcription. No certification is required for technical personnel to perform the test. No pretest quiet period is required. Calibration is performed at variable intervals (K. Daller, personal communication).

Currently IET is conducted at nine different sites. The length of training varies according to service, from 6 weeks in the Air Force to 12 weeks in the Marine Corps.8 The noise exposure varies according to service and among the five Army IET sites. The Navy (Great Lakes Recruit Training Center, Illinois), Marine Corps (Marine Corps Recruit Depots in Parris Island, South Carolina, and San Diego, California), and Army (at two sites, i.e., Fort Sill, Oklahoma, and Fort Benning, Georgia) perform universal DOEHRS-HC reference audiograms for recruits upon arrival. Fort Sill is the home of the artillery school and Fort Benning the infantry school. The Air Force (Lackland Air Force Base, San Antonio, Texas) performs reference audiograms at various times in IET. The other three Army sites (Fort Jackson, Fort Knox, and Fort Leonard Wood) review the MEPS screening audiograms and perform selected audiograms based on local criteria.

The argument has been made by various elements within the U.S. Army Training and Doctrine Command, USMEPCOM, and Medical Command that, because of constraints in manpower, funding, and time for IET medical in-processing, the MEPS screening audiogram should serve as a proxy for the reference audiogram. Alternative options would be to perform DOEHRS-HC reference audiograms at either MEPS or IET sites.