Editorial
JOURNAL OF WOMEN’S HEALTH Volume 23, Number 6, 2014 ª Mary Ann Liebert, Inc. DOI: 10.1089/jwh.2014.4880
Research on Gender Differences in Deployment Stress and Postdeployment Mental Health: Addressing Conceptual and Methodological Challenges and Expanding Our Research Agenda Dawne Vogt, PhD
he study by Macera and colleagues1 represents a nice addition to a growing body of research focused on understanding women’s, as compared to men’s, exposure to stressors in the war zone and the associated implications for postdeployment mental health. One of the main findings of the study is that combat exposure was associated with similar risk for posttraumatic stress disorder (PTSD) among Navy and Marine Corps women and men deployed in support of the recent U.S. wars in Iraq and Afghanistan. This finding is consistent with the results of several other recent studies,2,3,4,5 leading to the broader conclusion that female service members may be as resilient as male service members to the effects of combat exposure. Given women’s expanding role in the military, it seems likely that this topic will continue to generate attention in the coming years. To ensure that this research provides a meaningful contribution to the literature, it is important for investigators to consider a number of factors that may influence the conclusions that can be drawn from their study findings, including (1) the framing of the study question; (2) sample representativeness; (3) measurement of deployment stress exposure and postdeployment health; (4) inclusion of covariates; and (5) clinical significance. These factors are described below, followed by a discussion of future directions for empirical inquiry.
T
Framing of the Research Question
Research on this topic has typically addressed two conceptually related but independent questions. The first is the extent to which women and men differ in their risk for poor mental health after deployment. The second is the extent to which women and men differ in their risk for poor postdeployment mental health when they experience similar levels of deployment stress exposure. It is important to recognize that analyses that address the former do not inform the latter question. For example, just because women are found to be at higher risk for poor postdeployment mental health does not mean that they are necessarily more susceptible to the negative impact of particular deployment stress exposures, such as combat exposure. As Macera et al.
point out, gender differences in mental health could be a consequence of a variety of differences in women’s and men’s deployment experiences, as well as preexisting discrepancies in mental health.1 Likewise, the finding that particular deployment stress exposures have differential implications for the postdeployment mental health of women and men does not necessarily translate into gender differences in overall risk for poor postdeployment mental health. Women could be more vulnerable to the effects of combat exposure, for example, but not at higher overall risk for poor postdeployment health. In the Macera et al. study, findings revealed that although women were slightly more likely to screen positive for probable PTSD (a statistically significant finding that the authors point out is likely to be of little clinical significance), the relationship between combat exposure and PTSD was similar for women and men. Sample Representativeness and Reporting Bias
Sample representativeness is also a critical concern for research aimed at documenting gender differences in postdeployment mental health, as findings may be misleading or inaccurate if study samples overrepresent or underrepresent particular subgroups from the larger population. In their study, Macera and colleagues appropriately present information on how their study sample compares to the larger population in terms of demographic and military characteristics.1 Other factors may also be important to consider. For example, individuals with mental health problems may participate at either lower or higher rates depending on the recruitment strategy that is used. Reporting bias may also have implications for the validity of study findings. As Macera et al. note, active duty participants may be hesitant to report mental health conditions due to concerns about negative career consequences. Veterans Health Administration (VHA) patients may be concerned that endorsing or not endorsing certain deployment experiences will impact their access to VA benefits. It is important to consider how such factors may affect the generalizability of study results, and when feasible, address them either through recruitment strategies (e.g.,
Women’s Health Sciences Division, National Center for PTSD, VA Boston Healthcare System, & Boston University School of Medicine, Boston, Massachusetts.
485
486
targeted recruitment of underrepresented subgroups, clarifying data confidentiality to address privacy concerns) and/or analytical approaches (e.g., application of non-response bias weights). Measurement Considerations
Another important issue relates to the measurement of deployment stress exposure and postdeployment mental health. The focus of the Macera et al. study was on combat exposure and PTSD. Operational definitions and measurements of combat exposure have varied considerably in prior research, from very simplistic measurement of whether one served in a combat arms role (yes/no), to more comprehensive assessments of the overall severity of combat exposure, as reflected in assessments of both the frequency and intensity of exposure to a variety of combat-related experiences. The Macera study, which drew from preexisting screening data, operationalized combat as any level of exposure to three relatively severe examples of combat. Assessments of postdeployment mental health have also varied. The Macera et al. study relied on a dichotomous indicator of mental health (in this case, PTSD) that reflected whether or not individuals screened positive for the condition on a brief screening tool. Other studies (e.g., Vogt et al, 2011)4 have used measures that address the severity of PTSD symptoms. As noted by Macera et al, the use of different PTSD measures may lead to different results. Conceptually, these studies address different research questions, and researchers are encouraged to clearly describe their implications for the interpretation of study findings and when feasible, use validated measures that provide the most comprehensive assessments possible given the study question under investigation. Inclusion of Covariates
Researchers often include covariates in their examination of gender differences in deployment stress exposure and postdeployment mental health. This practice is intended to statistically equate women and men on potential confounding factors. The appropriateness of this choice depends on the nature of the study question under investigation. For example, the inclusion of deployment role as a covariate in analyses intended to document gender differences in combat exposure would be ill-advised, as deployment role is inextricably entwined with women’s and men’s combat exposure. While the inclusion of covariates can be useful when the goal is to explore potential mechanisms underlying gender differences, including covariates that are conceptually linked to gender can limit the interpretability and generalizability of findings when the study aim is to document differences in women’s and men’s experiences. As discussed at length by Miller and Chapman,6 it is critical that decisions about the inclusion of covariates be carefully considered and well justified. Clinical Significance
Researchers are also encouraged to attend to the clinical significance of their study findings, particularly among larger-sample studies, in which even very small differences may achieve statistical significance. Macera et al. are to be
VOGT
commended for their attention to this issue, as they appropriately recognize that the observed gender difference in PTSD in their study was so small as to be of little practical importance. While the bias against null findings is a concern for all research, the tendency to over-interpret relatively modest differences may be even greater for research that involves gender comparisons, given the focus on ‘‘differences’’ that is implicit in this field of study. Thus, it is imperative that researchers who study gender differences not only routinely present indicators of both statistical and clinical significance, but also discuss and interpret their findings with respect to both. Future Directions
The Macera et al. study adds to a growing body of research indicating that women may be no more likely than men to experience PTSD following exposure to combat. A key question for future inquiry is whether there are gender-specific moderators and mediators of the relationship between deployment stressors and postdeployment mental health. For example, given the expanding role of women in combat, it will be important to examine whether combat role moderates the impact of combat exposure on mental health. In addition, while most prior studies have focused on shorter-term outcomes, research is needed to examine whether longer-term outcomes of deployment stress exposure are similar for women and men. Ideally, such research would involve the application of longitudinal designs to address another limitation of prior research, which is the frequent reliance on cross-sectional designs. There is also a need to understand whether there are gender similarities or differences in the consequences of combat exposure and other deployment stressors for a broader range of mental, physical, and social health outcomes. Similarly, additional investigation is encouraged on the gender-specific implications of other deployment factors besides combat exposure. Macera and colleagues take an important step in this direction by examining gender-specific associations between a variety of deployment and military-related characteristics and PTSD. Future research would benefit from the examination of other important factors, including the role of family-related stressors in increasing risk for PTSD and other negative mental health sequelae. Most importantly, researchers need to clearly delineate how the research they do builds on and extends current knowledge. There is still a great deal to be learned about this important topic, and with attention to conceptual and methodological issues that impact the interpretation of our study findings, there is no doubt that the field will continue to flourish. Disclosure Statement
No competing financial interests exist. References
1. Macera CA, Aralis HJ, Highfill-McRoy R, Rauh MJ. Posttraumatic stress disorder after combat zone deployment in Navy and Marine Corps men and women. J Womens Health 2014;23:499–505. 2. Maguen S, Luxton DD, Skopp NA, Madden E. Gender differences in traumatic experiences and mental health in
GENDER DIFFERENCES IN DEPLOYMENT STRESS AND MENTAL HEALTH
active duty soldiers redeployed from Iraq and Afghanistan. J Psychiatr Res 2012;46311–316. doi: 10.1016/j.jpsychires. 2011.11.007. 3. Street AE, Gradus JL, Giasson HL, VogtD, Resick PA. Gender differences among veterans deployed in support of the wars in Afghanistan and Iraq. J Gen Intern Med 2013; 28:S556–S562. 4. Vogt D, Vaughn R, Glickman ME, Schultz M, Drainoni ML, Elwy R, Eisen S. Gender differences in combat-related stressors and their association with postdeployment mental health in a nationally representative sample of U.S. OEF/OIF veterans. J Abnorm Psychol 2011;120:797–806. 5. Woodhead C, Wessely S, Jones N, Fear NT, Hatch SL. Impact of exposure to combat during deployment to Iraq and
487
Afghanistan on mental health by gender. Psychol Med 2012;42:1985–1996. 6. Miller GA, Chapman JP. Misunderstanding analysis of covariance. J Abnorm Psychol 2001;110:40–48.
Address correspondence to: Dawne Vogt, PhD Women’s Health Sciences Division National Center for PTSD (116B-3) VA Boston Healthcare System 150 South Huntington Avenue Boston, MA 02130 E-mail: [email protected]
JOURNAL OF WOMEN’S HEALTH Volume 23, Number 6, 2014 ª Mary Ann Liebert, Inc. DOI: 10.1089/jwh.2014.4880
Research on Gender Differences in Deployment Stress and Postdeployment Mental Health: Addressing Conceptual and Methodological Challenges and Expanding Our Research Agenda Dawne Vogt, PhD
he study by Macera and colleagues1 represents a nice addition to a growing body of research focused on understanding women’s, as compared to men’s, exposure to stressors in the war zone and the associated implications for postdeployment mental health. One of the main findings of the study is that combat exposure was associated with similar risk for posttraumatic stress disorder (PTSD) among Navy and Marine Corps women and men deployed in support of the recent U.S. wars in Iraq and Afghanistan. This finding is consistent with the results of several other recent studies,2,3,4,5 leading to the broader conclusion that female service members may be as resilient as male service members to the effects of combat exposure. Given women’s expanding role in the military, it seems likely that this topic will continue to generate attention in the coming years. To ensure that this research provides a meaningful contribution to the literature, it is important for investigators to consider a number of factors that may influence the conclusions that can be drawn from their study findings, including (1) the framing of the study question; (2) sample representativeness; (3) measurement of deployment stress exposure and postdeployment health; (4) inclusion of covariates; and (5) clinical significance. These factors are described below, followed by a discussion of future directions for empirical inquiry.
T
Framing of the Research Question
Research on this topic has typically addressed two conceptually related but independent questions. The first is the extent to which women and men differ in their risk for poor mental health after deployment. The second is the extent to which women and men differ in their risk for poor postdeployment mental health when they experience similar levels of deployment stress exposure. It is important to recognize that analyses that address the former do not inform the latter question. For example, just because women are found to be at higher risk for poor postdeployment mental health does not mean that they are necessarily more susceptible to the negative impact of particular deployment stress exposures, such as combat exposure. As Macera et al.
point out, gender differences in mental health could be a consequence of a variety of differences in women’s and men’s deployment experiences, as well as preexisting discrepancies in mental health.1 Likewise, the finding that particular deployment stress exposures have differential implications for the postdeployment mental health of women and men does not necessarily translate into gender differences in overall risk for poor postdeployment mental health. Women could be more vulnerable to the effects of combat exposure, for example, but not at higher overall risk for poor postdeployment health. In the Macera et al. study, findings revealed that although women were slightly more likely to screen positive for probable PTSD (a statistically significant finding that the authors point out is likely to be of little clinical significance), the relationship between combat exposure and PTSD was similar for women and men. Sample Representativeness and Reporting Bias
Sample representativeness is also a critical concern for research aimed at documenting gender differences in postdeployment mental health, as findings may be misleading or inaccurate if study samples overrepresent or underrepresent particular subgroups from the larger population. In their study, Macera and colleagues appropriately present information on how their study sample compares to the larger population in terms of demographic and military characteristics.1 Other factors may also be important to consider. For example, individuals with mental health problems may participate at either lower or higher rates depending on the recruitment strategy that is used. Reporting bias may also have implications for the validity of study findings. As Macera et al. note, active duty participants may be hesitant to report mental health conditions due to concerns about negative career consequences. Veterans Health Administration (VHA) patients may be concerned that endorsing or not endorsing certain deployment experiences will impact their access to VA benefits. It is important to consider how such factors may affect the generalizability of study results, and when feasible, address them either through recruitment strategies (e.g.,
Women’s Health Sciences Division, National Center for PTSD, VA Boston Healthcare System, & Boston University School of Medicine, Boston, Massachusetts.
485
486
targeted recruitment of underrepresented subgroups, clarifying data confidentiality to address privacy concerns) and/or analytical approaches (e.g., application of non-response bias weights). Measurement Considerations
Another important issue relates to the measurement of deployment stress exposure and postdeployment mental health. The focus of the Macera et al. study was on combat exposure and PTSD. Operational definitions and measurements of combat exposure have varied considerably in prior research, from very simplistic measurement of whether one served in a combat arms role (yes/no), to more comprehensive assessments of the overall severity of combat exposure, as reflected in assessments of both the frequency and intensity of exposure to a variety of combat-related experiences. The Macera study, which drew from preexisting screening data, operationalized combat as any level of exposure to three relatively severe examples of combat. Assessments of postdeployment mental health have also varied. The Macera et al. study relied on a dichotomous indicator of mental health (in this case, PTSD) that reflected whether or not individuals screened positive for the condition on a brief screening tool. Other studies (e.g., Vogt et al, 2011)4 have used measures that address the severity of PTSD symptoms. As noted by Macera et al, the use of different PTSD measures may lead to different results. Conceptually, these studies address different research questions, and researchers are encouraged to clearly describe their implications for the interpretation of study findings and when feasible, use validated measures that provide the most comprehensive assessments possible given the study question under investigation. Inclusion of Covariates
Researchers often include covariates in their examination of gender differences in deployment stress exposure and postdeployment mental health. This practice is intended to statistically equate women and men on potential confounding factors. The appropriateness of this choice depends on the nature of the study question under investigation. For example, the inclusion of deployment role as a covariate in analyses intended to document gender differences in combat exposure would be ill-advised, as deployment role is inextricably entwined with women’s and men’s combat exposure. While the inclusion of covariates can be useful when the goal is to explore potential mechanisms underlying gender differences, including covariates that are conceptually linked to gender can limit the interpretability and generalizability of findings when the study aim is to document differences in women’s and men’s experiences. As discussed at length by Miller and Chapman,6 it is critical that decisions about the inclusion of covariates be carefully considered and well justified. Clinical Significance
Researchers are also encouraged to attend to the clinical significance of their study findings, particularly among larger-sample studies, in which even very small differences may achieve statistical significance. Macera et al. are to be
VOGT
commended for their attention to this issue, as they appropriately recognize that the observed gender difference in PTSD in their study was so small as to be of little practical importance. While the bias against null findings is a concern for all research, the tendency to over-interpret relatively modest differences may be even greater for research that involves gender comparisons, given the focus on ‘‘differences’’ that is implicit in this field of study. Thus, it is imperative that researchers who study gender differences not only routinely present indicators of both statistical and clinical significance, but also discuss and interpret their findings with respect to both. Future Directions
The Macera et al. study adds to a growing body of research indicating that women may be no more likely than men to experience PTSD following exposure to combat. A key question for future inquiry is whether there are gender-specific moderators and mediators of the relationship between deployment stressors and postdeployment mental health. For example, given the expanding role of women in combat, it will be important to examine whether combat role moderates the impact of combat exposure on mental health. In addition, while most prior studies have focused on shorter-term outcomes, research is needed to examine whether longer-term outcomes of deployment stress exposure are similar for women and men. Ideally, such research would involve the application of longitudinal designs to address another limitation of prior research, which is the frequent reliance on cross-sectional designs. There is also a need to understand whether there are gender similarities or differences in the consequences of combat exposure and other deployment stressors for a broader range of mental, physical, and social health outcomes. Similarly, additional investigation is encouraged on the gender-specific implications of other deployment factors besides combat exposure. Macera and colleagues take an important step in this direction by examining gender-specific associations between a variety of deployment and military-related characteristics and PTSD. Future research would benefit from the examination of other important factors, including the role of family-related stressors in increasing risk for PTSD and other negative mental health sequelae. Most importantly, researchers need to clearly delineate how the research they do builds on and extends current knowledge. There is still a great deal to be learned about this important topic, and with attention to conceptual and methodological issues that impact the interpretation of our study findings, there is no doubt that the field will continue to flourish. Disclosure Statement
No competing financial interests exist. References
1. Macera CA, Aralis HJ, Highfill-McRoy R, Rauh MJ. Posttraumatic stress disorder after combat zone deployment in Navy and Marine Corps men and women. J Womens Health 2014;23:499–505. 2. Maguen S, Luxton DD, Skopp NA, Madden E. Gender differences in traumatic experiences and mental health in
GENDER DIFFERENCES IN DEPLOYMENT STRESS AND MENTAL HEALTH
active duty soldiers redeployed from Iraq and Afghanistan. J Psychiatr Res 2012;46311–316. doi: 10.1016/j.jpsychires. 2011.11.007. 3. Street AE, Gradus JL, Giasson HL, VogtD, Resick PA. Gender differences among veterans deployed in support of the wars in Afghanistan and Iraq. J Gen Intern Med 2013; 28:S556–S562. 4. Vogt D, Vaughn R, Glickman ME, Schultz M, Drainoni ML, Elwy R, Eisen S. Gender differences in combat-related stressors and their association with postdeployment mental health in a nationally representative sample of U.S. OEF/OIF veterans. J Abnorm Psychol 2011;120:797–806. 5. Woodhead C, Wessely S, Jones N, Fear NT, Hatch SL. Impact of exposure to combat during deployment to Iraq and
487
Afghanistan on mental health by gender. Psychol Med 2012;42:1985–1996. 6. Miller GA, Chapman JP. Misunderstanding analysis of covariance. J Abnorm Psychol 2001;110:40–48.
Address correspondence to: Dawne Vogt, PhD Women’s Health Sciences Division National Center for PTSD (116B-3) VA Boston Healthcare System 150 South Huntington Avenue Boston, MA 02130 E-mail: [email protected]
