Homosexuality-related stigma and sexual risk behaviors among men who have sex with men in Hanoi, Vietnam.

This article examined the associations between three forms of homosexuality-related stigma (enacted, perceived, and internalized homosexual stigmas) with risky sexual behaviors, and to describe the mechanisms of these associations, among men who have sex with men (MSM) in Hanoi, Vietnam. We used respondent-driven sampling (RDS) to recruit 451 MSM into a cross-sectional study conducted from August 2010 to January 2011. Data were adjusted for recruitment patterns due to the RDS approach; logistic regression and path analyses were performed. Participants were young and single; most had attended at least some college. Nine out of ten participants engaged in sexual behaviors at moderate to high risk levels. Compared to those who had no enacted homosexual stigma, men having low and high levels of enacted homosexual stigma, respectively, were 2.23 times (95 % CI 1.35-3.69) and 2.20 times (95 % CI 1.04-4.76) more likely to engage in high levels of sexual risk behaviors. In addition, there was an indirect effect of perceived homosexual stigma and internalized homosexual stigma on sexual risk behaviors through depression and drug and alcohol use. Our study provides valuable information to our understanding of homosexual stigma in Vietnam, highlighting the need for provision of coping skills against stigma to the gay community and addressing drinking and drug use among MSM, to improve the current HIV prevention interventions in Vietnam.

Comparison of surveillance sample demographics over two cycles of the National HIV Behavioral Surveillance Project, Houston, Texas.

We examined differences in sample demographics across cycles of the National HIV Behavioral Surveillance project, that examines HIV risk behaviors among men who have sex with men (MSM), injection drug users (IDU), and heterosexuals living in areas of high HIV prevalence (HET). MSM were recruited through venue-based sampling, and IDU and HET through respondent driven sampling (RDS). RDS data were weighted to account for sampling bias. We compared crude prevalence estimates from MSM1 (2004) to those from MSM2 (2008) for demographic factors known to influence risky sexual and drug-use behaviors. We compared crude and adjusted prevalence estimates for IDU1 (2005) and IDU2 (2009) and HET1 (2006) and HET2 (2010). In the MSM cycle, we found differences in age, and the proportions seeking medical care and reporting a recent arrest. There were no differences in the comparison of crude and weighted estimates for the RDS collected samples, nor were there differences comparing HET1 and HET2 weighted estimates. IDU2 recruited a larger proportion of males, and had a higher percent who graduated from high school and who reported recent medical care and a previous HIV test. Differences across MSM cycles may be related to differences in venues identified for each cycle. Differences in the IDU cycles may be due to an effort on our part to increase the racial/ethnic and drug-use diversity of the sample in IDU2. Our findings show the importance of formative work for both venue-based and RDS samples to increase understanding of the dimensions that affect social networks and the dynamics of populations in space and time. With familiarity of the target population, we believe that both venue-based and RDS recruitment approaches for NHBS work well and can be used to evaluate changes in risky sexual and drug use behaviors and in HIV testing behaviors.

Use of latent class analysis approach to describe drug and sexual HIV risk patterns among injection drug users in Houston, Texas.

Following latent class analysis (LCA) approach we examined patterns of HIV risk using two related domains of behavior: drug use, and sexual activity among 523 injection drug users (IDUs) recruited into the 2009 National HIV behavioral surveillance system. Using posterior probability of endorsing six drug and sexual items, we identified three distinct classes representing underlying HIV risk. Forty percent of our participants were at highest risk, 25 % at medium risk, and 35 % at lowest risk for HIV infection. Compared to the Lowest-risk class members, the Highest-risk class members had riskier drug and sexual behaviors and had higher prevalence of HIV cases (6 vs. 4 %). This analysis underscores the merit of LCA to empirically identify risk patterns using multiple indicators and our results show HIV risk varies among IDUs as their drug and sexual behaviors. Tailored and targeted prevention and treatment interventions for the dual risk pattern are required rather than for drug or sexual risk in silos.

A hybrid method in combining treatment effects from matched and unmatched studies.

The most common data structures in the biomedical studies have been matched or unmatched designs. Data structures resulting from a hybrid of the two may create challenges for statistical inferences. The question may arise whether to use parametric or nonparametric methods on the hybrid data structure. The Early Treatment for Retinopathy of Prematurity study was a multicenter clinical trial sponsored by the National Eye Institute. The design produced data requiring a statistical method of a hybrid nature. An infant in this multicenter randomized clinical trial had high-risk prethreshold retinopathy of prematurity that was eligible for treatment in one or both eyes at entry into the trial. During follow-up, recognition visual acuity was accessed for both eyes. Data from both eyes (matched) and from only one eye (unmatched) were eligible to be used in the trial. The new hybrid nonparametric method is a meta-analysis based on combining the Hodges-Lehmann estimates of treatment effects from the Wilcoxon signed rank and rank sum tests. To compare the new method, we used the classic meta-analysis with the t-test method to combine estimates of treatment effects from the paired and two sample t-tests. We used simulations to calculate the empirical size and power of the test statistics, as well as the bias, mean square and confidence interval width of the corresponding estimators. The proposed method provides an effective tool to evaluate data from clinical trials and similar comparative studies.

Effectiveness of respondent driven sampling to recruit undocumented Central American immigrant women in Houston, Texas for an HIV behavioral survey.

Respondent driven sampling (RDS) is widely used for HIV behavioral research among sex workers, drug users, and other hidden populations, but has had limited application in immigrant populations in the U.S. In 2010, we used RDS to recruit undocumented Central American immigrant women in Houston, Texas for an HIV behavioral survey. Beginning with three initial participants we recruited 226 women within 16 weeks. Social networks were dense and participants adopted the recruitment system with reasonable ease. Homophily scores indicated moderate within-group preference by country of origin. However, cross-group recruitment was sufficient to achieve a diverse sample that attained equilibrium for all demographic and sexual behavior characteristics. Overall, RDS was easy to implement, attained a large sample in a relatively short period of time, and reached an otherwise hidden population. Our results suggest that RDS is an effective method for recruiting undocumented Latina immigrants for HIV behavioral surveys.

Clustered drug and sexual HIV risk among a sample of middle-aged injection drug users, Houston, Texas.

Recent studies have reported a clustered pattern of high-risk drug using and sexual behaviors among younger injection drug users (IDUs), however, no studies have looked at this clustering pattern in relatively older IDUs. This analysis examines the interplay and overlap of drug and sexual HIV risk among a sample of middle-aged, long-term IDUs in Houston, Texas. Our study includes 452 eligible IDUs, recruited into the 2009 National HIV Behavioral Surveillance project. Four separate multiple logistic regression models were built to examine the odds of reporting a given risk behavior. We constructed the most parsimonious multiple logistic regression model using a manual backward stepwise process. Participants were mostly male, older (mean age: 49.5±6.63), and nonHispanic Black. Prevalence of receptive needle sharing as well as having multiple sex partners and having unprotected sex with a partner in exchange for money, drugs, or other things at last sex were high. Unsafe injecting practices were associated with high-risk sexual behaviors. IDUs, who used a needle after someone else had injected with it had higher odds of having more than three sex partners (odds ratio (OR) = 2.10, 95% confidence interval (CI): 1.40-3.12) in last year and who shared drug preparation equipment had higher odds of having unprotected sex with an exchange partner (OR = 3.89, 95% CI: 1.66-9.09) at last sex. Additionally, homelessness was associated with unsafe injecting practices but not with high-risk sexual behaviors. Our results show that a majority of the sample IDUs are practicing sexual as well as drug-using HIV risk behaviors. The observed clustering pattern of drug and sexual risk behavior among this middle-aged population is alarming and deserve attention of HIV policy-makers and planners.

Prevalence of HIV risk behaviors among undocumented Central American immigrant women in Houston, Texas.

Undocumented Central American immigrants in the United States are disproportionately affected by HIV infection. However, epidemiological data on sexual behaviors among undocumented women are sparse and the extent to which behaviors vary by duration of residence in the U.S.is largely unknown. In 2010, we used respondent driven sampling to conduct an HIV behavioral survey among Central American immigrant women residing in Houston, Texas without a valid U.S. visa or residency papers. Here we describe the prevalence of sexual risk behaviors and compare recent (5 years or less in the U.S.) and established immigrants (over 5 years in the U.S.) to elucidate changes in sexual risk behaviors over time. Our data suggest that recent immigrants have less stable sexual partnerships than established immigrants, as they are more likely to have multiple and concurrent sexual partnerships, as well as partnerships of shorter duration.

Bisphosphonates in the treatment of patients with lung cancer and metastatic bone disease: a systematic review and meta-analysis.

PURPOSE: Bisphosphonates are known to prevent skeletal-related events (SREs) in advanced breast cancer, prostate cancer, and multiple myeloma. This systematic review assessed the efficacy of bisphosphonates in preventing SREs, controlling pain, and overall survival in patients with bone metastases from lung cancer. METHODS: We searched MEDLINE, EMBASE, Web of Science, and the Cochrane Library databases through November 10, 2011 for controlled trials that included lung cancer patients with bone metastases treated with bisphosphonates. Two reviewers independently extracted data on pain control, survival, and SREs and evaluated the quality of each study. Meta-analyses were performed when there were two or more trials with similar outcomes. RESULTS: Twelve trials met our inclusion criteria and included 1,767 patients. Studies were placebo-controlled, or had compared bisphosphonates with other modalities (chemotherapy, radiation therapy, or radioisotope therapy), or had used different bisphosphonates as active controls. Randomized controlled trials did not report adequate descriptions of randomization procedures, allocation concealment, and blinding, resulting in low-quality scores. Patients treated with zoledronic acid + chemotherapy had fewer SREs than those receiving chemotherapy alone (relative risk (RR) 0.81, 95 % confidence interval (CI) 0.67-0.97). Pain control improved when a bisphosphonate was added to another treatment modality (chemotherapy or radiation; RR 1.18, 95 %CI 1.0-1.4). Bisphosphonate therapy improved survival compared to controls, but the difference failed to reach statistical significance (mean of 72 days, 95 %CI -8.9 to 152.9). CONCLUSIONS: Treatment with bisphosphonates reduced SREs, improved pain control, and showed a trend to increased survival. Bisphosphonates should be used in the treatment of patients with lung cancer and bone metastases.

The prevalence of spirituality, optimism, depression, and fatalism in a bi-ethnic stroke population.

To provide insight into the reduced post-stroke all-cause mortality among Mexican Americans, we explored ethnic differences in the pre-stroke prevalence of (1) spirituality, (2) optimism, (3) depression, and (4) fatalism in a Mexican American and non-Hispanic white stroke population. The Brain Attack Surveillance in Corpus Christi (BASIC) project is a population-based stroke surveillance study in Nueces County, Texas. Seven hundred ten stroke patients were queried. For fatalism, optimism, and depression scales, unadjusted ethnic comparisons were made using linear regression models. Regression models were also used to explore how age and gender modify the ethnic associations after adjustment for education. For the categorical spirituality variables, ethnic comparisons were made using Fisher's exact tests. Mexican Americans reported significantly more spirituality than non-Hispanic whites. Among women, age modified the ethnic associations with pre-stroke depression and fatalism but not optimism. Mexican American women had more optimism than non-Hispanic white women. With age, Mexican American women had less depression and fatalism, while non-Hispanic white women had more fatalism and similar depression. Among men, after adjustment for education and age, there was no ethnic association with fatalism, depression, and optimism. Spirituality requires further study as a potential mediator of increased survival following stroke among Mexican Americans. Among women, evaluation of the role of optimism, depression, and fatalism as they relate to ethnic differences in post-stroke mortality should be explored.

Fatalism, optimism, spirituality, depressive symptoms, and stroke outcome: a population-based analysis.

BACKGROUND AND PURPOSE: We sought to describe the association of spirituality, optimism, fatalism, and depressive symptoms with initial stroke severity, stroke recurrence, and poststroke mortality. METHODS: Stroke cases from June 2004 to December 2008 were ascertained in Nueces County, TX. Patients without aphasia were queried on their recall of depressive symptoms, fatalism, optimism, and nonorganizational spirituality before stroke using validated scales. The association between scales and stroke outcomes was studied using multiple linear regression with log-transformed National Institutes of Health Stroke Scale and Cox proportional hazards regression for recurrence and mortality. RESULTS: Six hundred sixty-nine patients participated; 48.7% were women. In fully adjusted models, an increase in fatalism from the first to third quartile was associated with all-cause mortality (hazard ratio, 1.41; 95% CI, 1.06-1.88) and marginally associated with risk of recurrence (hazard ratio, 1.35; 95% CI, 0.97-1.88), but not stroke severity. Similarly, an increase in depressive symptoms was associated with increased mortality (hazard ratio, 1.32; 95% CI, 1.02-1.72), marginally associated with stroke recurrence (HR, 1.22; 95% CI, 0.93-1.62), and with a 9.0% increase in stroke severity (95% CI, 0.01-18.0). Depressive symptoms altered the fatalism-mortality association such that the association of fatalism and mortality was more pronounced for patients reporting no depressive symptoms. Neither spirituality nor optimism conferred a significant effect on stroke severity, recurrence, or mortality. CONCLUSIONS: Among patients who have already had a stroke, self-described prestroke depressive symptoms and fatalism, but not optimism or spirituality, are associated with increased risk of stroke recurrence and mortality. Unconventional risk factors may explain some of the variability in stroke outcomes observed in populations and may be novel targets for intervention.

Cost-effectiveness of white blood cell growth factor use among a large nationwide cohort of elderly non-Hodgkin's lymphoma patients treated with chemotherapy.

OBJECTIVE: To determine the cost-effectiveness (as measured as cost per life-year saved) of white blood cell growth factor or colony-stimulating factor (CSF) use among a large cohort of elderly non-Hodgkin's lymphoma (NHL) patients in a real-world setting. METHODS: We identified 13,203 NHL patients from the Surveillance, Epidemiology, and End Results (SEER)-Medicare database who received the diagnosis from 1992 to 2002 and who received chemotherapy within 12 months of diagnosis. Benefit (effectiveness) of CSF use (primary and secondary prophylaxis) was measured as observed improvement in overall survival. Costs for each patient were calculated by adding the cumulative reimbursement amounts from Medicare claims. Cost-effectiveness was estimated by modeling the joint influence of CSF use on both costs and effectiveness using a propensity-score net monetary benefit approach. RESULTS: Primary prophylactic CSF use was cost-effective at lower willingness-to-pay thresholds, whereas at higher thresholds, not providing prophylactic CSF became the cost-effective strategy. For secondary prophylactic CSF use among patients experiencing neutropenia, fever, and/or infection, the opposite trend was observed. For low willingness-to-pay thresholds (<$20,000 per life-year gained), not administering CSF was the cost-effective strategy, whereas CSF use became cost-effective as willingness to pay increased (from $100,000+ per life-year gained). CONCLUSION: To our knowledge, this is the first large population-based study to empirically measure the cost-effectiveness of CSF among NHL patients treated with chemotherapy. CSF use as primary or secondary prophylaxis may be a cost-effective strategy depending on society's (or payers') willingness to pay for improvements in outcomes.

Late HIV diagnosis in Houston/Harris County, Texas, 2000-2007.

This cross-sectional study aimed to evaluate the prevalence and predictive factors associated with late HIV diagnoses in Houston, Texas using surveillance data. Study subjects were Houston/Harris County residents, 13 years or older, diagnosed with HIV and reported to the Houston Department of Health and Human Services. Late HIV diagnosis was defined as an AIDS diagnosis within three months of an HIV diagnosis. Logistic regression was used to investigate the association between late HIV diagnoses and predictive factors. We found 31% of the study population had late HIV diagnoses. The Hispanic population, men, older individuals, heterosexuals, and those diagnosed in private facilities were more likely to receive late HIV diagnoses. Sensitivity analysis was conducted to evaluate the effect of time from HIV to AIDS diagnosis on the prevalence of a late diagnosis, and on the predictors of late diagnosis. The sensitivity analysis showed time affects prevalence, but not the odds ratios of the risk factors for late diagnosis. This finding suggests HIV prevention programs should specifically target these populations at risk for late HIV diagnosis to encourage frequent HIV testing.

Gender differences in social support and depression among injection drug users in Houston, Texas.

BACKGROUND: Injection drug is the second most frequent HIV/AIDS exposure in the United States. Social support and depression may mediate risky behaviors among drug injectors. OBJECTIVES: To describe differences in perceived social support and depressive symptoms between male and female injection drug users, and to describe factors associated with depressive symptoms. METHODS: Using respondent-driven sampling, we recruited and interviewed injection drug users in Houston, Texas. Data were from the Centers for Disease Control and Prevention's National HIV Behavioral Surveillance Program. We used the short Center for Epidemiologic Studies Depression Scale (CES-D 10) and scales for perceived social support from family, friends, and significant others from the Multidimensional Scale of Perceived Social Support. Four-hundred seventy-one participants had complete data and were included in this analysis. RESULTS: Seventy-five percent of male and female participants had CES-D scores indicating depressive symptoms. In a multivariate logistic regression, depressive symptoms among men were positively associated with frequent use of speedballs (injecting heroin and cocaine together) and never having tested for HIV, and negatively associated with perceived social support from a special person. Among women, depressive symptoms were positively associated with currently smoking cigarettes, having no health insurance, and more years of injection drug use, and negatively associated with perceived social support from a special person. CONCLUSIONS: Lack of social support from a special person or significant other was associated with depressive symptoms in both males and females. Our findings suggest that depression and social support should be addressed when developing HIV prevention programs among injection drug users.

Sexual compulsivity and high-risk sex among Latino men: the role of internalized homonegativity and gay organizations.

The objective of this study was to measure the correlation between compulsive sexual behavior (CSB) and internalized homonegativity (IH) and determine their association with unprotected anal intercourse in Latino men who have sex with men. Nine hundred sixty-three Latino men completed an Internet survey (MINTS study) in 2002 and provided data on two scale exposures. Logistic regression was used to test interactions and generate effect estimates. Higher IH and association with gay organizations modified the effect of CSB on high-risk sex. Drug and alcohol use also contributed to risk behavior for this subgroup. Overall, CSB had a strong association with high-risk sex. IH and gay organization membership may moderate this relationship, which illuminates an additional factor to consider in studying sexual risk-taking. Further work is needed to validate a path from IH and high-risk sex that incorporates drug or alcohol use.

Epidemiology of infections in women.

This article describes the epidemiologic profiles of sexually transmitted infections seen in US women. We present a brief description of the infectious agent, describe the epidemiology of the infection among women in terms of race/ethnicity and age (if those data are available), and present what is known about the behavioral risk factors associated with acquisition.

Social and behavioral determinants of consistent condom use among female commercial sex workers in Ghana.

This study investigated the social and behavioral predictors of consistent condom use among female commercial sex workers (FCSWs) in Ghana. Four hundred fifty street commercial sex workers were interviewed in Accra, Kumasi and Techiman. The level of condom education was very low (14%); however consistent condom use (all the time) with clients was relatively high (49.6%). Two hundred seventy-seven of the participants did not use condoms all the time.

Current perspectives in the USA on the diagnosis and treatment of pelvic inflammatory disease in adolescents.

In this review, the epidemiology, diagnosis, and treatment of pelvic inflammatory disease (PID) are discussed from a USA perspective and the difficulties that USA adolescents face in recognizing and seeking care for PID and other sexually transmitted infections (STIs) are emphasized. Females aged 15-24 years have the highest incidence of cervical infection with Chlamydia trachomatis and Neisseria gonorrheae, the principal causes of PID. PID is common in this age group. However, the incidence of PID in the USA is not known, because it is not a reportable disease, and because clinicians vary in the criteria used for the diagnosis. The Centers for Disease Control and Prevention (CDC) recommended the following diagnostic criteria that include lower abdominal or pelvic pain and at least one of the following: adnexal tenderness or cervical motion tenderness or uterine tenderness. Because PID can have serious sequelae, the criteria emphasize sensitivity (few false-negatives) at the expense of specificity (some false-positives). Patients who have PID are usually treated in the outpatient setting, following the CDC's Guidelines for the Treatment of Sexually Transmitted Diseases 2015. They receive one dose of an intramuscular cephalosporin, together with 2 weeks of oral doxy cycline, and sometimes oral metronidazole. Improvement should usually be evident in 3 days. The USA does not offer comprehensive sex education for adolescents in public or private schools. Adolescents are unlikely to recognize the symptoms of PID and seek medical treatment. Confidentiality is important to adolescents, and low cost or free sources of confidential care are uncommon, making it unlikely that an adolescent would seek care even if she suspected an STI. The CDC has concluded that screening programs for chlamydia and gonorrhea infection help prevent PID; however, the lack of appropriate sources of care makes adolescents' participation in screening programs unlikely.

Health Care Use and HIV-Related Behaviors of Black and Latina Transgender Women in 3 US Metropolitan Areas: Results From the Transgender HIV Behavioral Survey.

PURPOSE: HIV prevalence estimates among transgender women in the United States are high, particularly among racial/ethnic minorities. Despite increased HIV risk and evidence of racial disparities in HIV prevalence among transgender women, few data are available to inform HIV prevention efforts. METHODS: A transgender HIV-related behavioral survey conducted in 2009 in 3 US metropolitan areas (Chicago, Houston, and Los Angeles County), used respondent-driven sampling to recruit 227 black (n = 139) and Latina (n = 88) transgender women. We present descriptive statistics on sociodemographic, health care, and HIV-risk behaviors. RESULTS: Of 227 transgender women enrolled, most were economically and socially disadvantaged: 73% had an annual income of less than $15,000; 62% lacked health insurance; 61% were unemployed; and 46% reported being homeless in the past 12 months. Most (80%) had visited a health care provider and over half (58%) had tested for HIV in the past 12 months. Twenty-nine percent of those who reported having an HIV test in the past 24 months self-reported being HIV positive. Most of the sample reported hormone use (67%) in the past 12 months and most hormone use was under clinical supervision (70%). Forty-nine percent reported condomless anal sex in the past 12 months and 16% reported ever injecting drugs. CONCLUSION: These findings reveal the socioeconomic challenges and behavioral risks often associated with high HIV risk reported by black and Latina transgender women. Despite low health insurance coverage, the results suggest opportunities to engage transgender women in HIV prevention and care given their high reported frequency of accessing health care providers.

HIV Among MSM and Heterosexual Women in the United States: An Ecologic Analysis.

BACKGROUND: Phylogenetic studies show links between heterosexual women and men who have sex with men (MSM) that are more numerous than from heterosexual men to women suggesting that HIV infections among heterosexual women may stem from MSM. Poor communities have been associated with high rates of HIV among heterosexual women. Our analysis investigates potential transmission of HIV between MSM and female heterosexuals. METHODS: National HIV Behavioral Surveillance data describe transmission risk behaviors of MSM, and HIV case reporting data describe the percentages of cases that are attributed to transmission risk categories. We examined correlations between the percentages of men who were MSM who also have sex with women and female heterosexual cases. We also examined census data to characterize each city in terms of poverty level and race/ethnicity makeup. RESULTS: There was a high correlation (0.93) between the percentage of reported living HIV cases attributed to male heterosexual contact and female heterosexual contact and a moderate nonsignificant correlation (0.49) between the percentage of MSM who were men who have sex with men and women (MSMW) in National HIV Behavioral Surveillance and the percentage of reported cases that were attributed to female heterosexual contact suggesting some potential overlap. Cities with high levels of poverty and African American/Black residents had higher levels of MSMW and higher levels of heterosexual female cases. CONCLUSIONS: Addressing HIV in cities with high levels of MSMW may have the dual effect of improving the health of MSM populations that have a high burden of HIV and to improve the health of their larger communities.

Stroke burden in Mexican Americans: the impact of mortality following stroke.

PURPOSE: To estimate ethnic-specific all-cause mortality risk following ischemic stroke and to compare mortality risk by ethnicity. METHODS: DATA from the Brain Attack Surveillance in Corpus Christi Project, a population-based stroke surveillance study, were used. Stroke cases between January 1, 2000 and December 31, 2002 were identified from emergency department (ED) and hospital sources (n = 1,234). Deaths for the same period were identified from the surveillance of stroke cases, the Texas Department of Health, the coroner, and the Social Security Death Index. Ethnic-specific all-cause cumulative mortality risk was estimated at 28 days and 36 months using Kaplan Meier analysis. Cox proportional hazards regression was used to compare mortality risk by ethnicity. RESULTS: Cumulative 28-day all-cause mortality risk for Mexican Americans (MAs) was 7.8% and for non-Hispanic whites (NHWs) was 13.5%. Cumulative 36-month all-cause mortality risk was 31.3% in MAs and 47.2% in NHWs. MAs had lower 28-day (RR = 0.58; 95% CI: 0.41, 0.84) and 36-month all-cause mortality risk (RR = 0.79, 95% CI: 0.64, 0.98) compared with NHWs, adjusted for confounders. CONCLUSIONS: Better survival after stroke in MAs is surprising considering their similar stroke subtype and severity compared with NHWs. Social or psychological factors, which may explain this difference, should be explored.