LeardMann et al. BMC Public Health 2010, 10:437 http://www.biomedcentral.com/1471-2458/10/437 among the strongest predictors for PTSD among mili- tary service members [8]. Another study of 221 female veterans who visited the Veterans Affairs Healthcare System between 1998 and 1999 reported that childhood trauma, including emotional abuse, physical abuse, sex- ual abuse, emotional neglect, and physical neglect, con- tributed to the severity of PTSD [13]. Lapp [14] found that 69% of male veterans with a primary admitting diagnosis of PTSD had self-reported suffering either sex- ual or physical abuse as a child. Similarly, higher rates of childhood physical abuse were reported in patients with PTSD in a study of Vietnam combat veterans [15]. More recently, a study reported an association between ACE and the expression of mental illness among adults [16]. Among male US soldiers, ACE have been asso- ciated with an increase of mental health outcomes [17]. Also, an association was found between childhood adversity and PTSD symptoms among UK military per- sonnel who had been deployed to Iraq [18]. The Recruit Assessment Program (RAP), launched June 2001 at the Marine Corps Recruit Depot (MCRD) in San Diego, California, was designed to collect baseline health data on Marine recruits. The RAP survey is administered during the first few days of recruit train- ing. The recruits are informed that the survey is volun- tary and their responses will not disqualify them from military service. The main goal of RAP is to collect and examine health and behavioral data at service entrance to better understand service-related exposures and health outcomes [19]. An association between ACE and mental health out- comes has been documented, however most previous studies have assessed ACE after the traumatic event, introducing potential biases related to recall and report- ing [13-16,18]. The objective of this study was to pro- spectively examine the association between ACE and PTSD among Marines following deployment in support of military conflicts in Iraq and Afghanistan. Methods Population and Data Sources As of March 2010, over 130,000 recruits had completed a RAP survey during initial training, with a response rate over 95%. Development of the RAP survey was a collaborative effort of public health officials, clinicians, and researchers from the Department of Defense, Veter- ans Health Administration, and Department of Health and Human Services. The survey instrument includes questions on demographics, health, family history, tobacco and alcohol use, mental health history, and ACE [19]. Adverse childhood experience questions on the RAP survey were derived from the Adverse Childhood Experiences Study [20,21], which adapted questions Page 2 of 8 from the Childhood Trauma Questionnaire [22], Con- flict Tactics Scales [23], and sexual abuse questions from Wyatt [24]. Using questions framed to reflect experiences prior to age 17 years, 7 ACE categories were assessed in the current study: (1) physical neglect (lack of care and protection), (2) emotional neglect (lack of feeling loved), (3) physical abuse (pushed, grabbed, shoved, or slapped), (4) emotional abuse (was sworn at, insulted, or put down), (5) sexual abuse, (6) domestic violence, and (7) family history of mental illness or alco- hol abuse. Each ACE category was based on 1 self- reported question from the RAP survey, with the excep- tion of family history of mental illness and alcohol abuse, which was assessed using 2 questions. The 7 ACE categories were evaluated as dichotomous “yes” or “no” responses. Questions with a 5-point scale were dichotomized based on criteria used by Dube et al. [21]; for neglect, a positive response was classified if respon- ders reported neglect “often” or more frequently. A 3-level categorical variable was created to evaluate over- all occurrences of childhood adversity: no history of ACE, history of ACE in 1 category, or history of ACE in 2 or more categories. Other questions from the RAP survey were used as covariates in multivariable modeling, including educa- tion, parental education, number of close friends, alco- hol-drinking behavior, smoking status, self-reported mental health status, visiting a mental health profes- sional in the 5 years prior to survey completion, and prior traumatic event (including being in a severe acci- dent, seeing someone badly injured or killed, being attacked or assaulted, threatened with a weapon, or being raped). Deployment data, obtained from the Defense Man- power Data Center (DMDC), include all service mem- bers deployed in support of the conflicts in Iraq and Afghanistan since September 2001. Length of deploy- ment was defined as the cumulative number of days deployed after completion of the RAP survey until first mental health event, 2 years after last deployment, or June 30, 2005, whichever came first. Marital status, age at first deployment, Armed Forces Qualification Test (AFQT) score, and race/ethnicity were also acquired from DMDC. The AFQT score is computed using four tests that measure knowledge in high school level subjects. Patient medical records were used to determine diag- nosis for PTSD, and mental health disorders that may be manifestations of PTSD. Hospitalization and outpati- ent data sources, including all visits to military treat- ment facilities as well as civilian visits billed to the military, were used in these analyses. All diagnostic fields were scanned for PTSD (ICD-9-CM codes 308 and 309.8) and other mental health disorders (ICD-9-