Differential item functioning (DIF) of SF-12 and Q-LES-Q-SF items among french substance users

Profiles of cannabis users and impact on cannabis cessation

Although cannabis was legalized in Canada in 2018 and is one of the most used substances in Canada, few studies have examined how individuals with different patterns of cannabis use differ in their attempts to decrease or abstain from cannabis. The current study examined how groups of cannabis users, which were formed on the basis of demographic characteristics, substance use patterns, mental health symptoms, and self-reported quality of life differed on their experiences with cannabis cessation. A sample of 147 Canadian adult participants who had attempted to decrease or quit cannabis were recruited from the community (n = 84, 57.14%) and crowdsourcing (n = 63, 42.86%). Four profiles of cannabis users emerged using a Latent Profile Analysis: low-risk (n = 62, 42.18%), rapidly escalating high-risk (n = 40, 27.21%), long-term high severity (n = 35, 23.81%), and long-term lower severity (n = 10, 6.80%). Individuals in the rapidly escalating profile had attempted to decrease their cannabis use more times compared to other profiles. More participants in the long-term high severity group found their use stayed the same or got worse after their last cessation attempt, compared to the low-risk group where more individuals indicated their use stopped. The results of the current study indicate that cannabis users differ in their attempts at reducing or ceasing cannabis use and that they may benefit from different intensity of cannabis interventions.

Sex-related differential item functioning of the Jenkins Sleep Scale: a cross-sectional study among 77 967 employees in the Finnish public sector

OBJECTIVES

To investigate if the Jenkins Sleep Scale (JSS) demonstrates sex-related differential item functioning (DIF).

DESIGN

Cross-sectional study.

SETTING

Survey data from the Finnish Public Sector study (2015-2017).

PARTICIPANTS

77 967 employees in the Finnish public sector, with a mean age of 51.9 (SD 13.1) years and 82% women.

OUTCOME MEASURES

Item response theory estimates: difficulty and discrimination parameters of the JSS and differences in these parameters between men and women.

RESULTS

The mean JSS total score was 6.4 (4.8) points. For all four items of the JSS, the difficulty parameter demonstrated a slight shift towards underestimation of the severity of sleep difficulties. The discrimination ability of all four items was moderate to high. For the JSS composite score, overall discrimination ability was moderate (0.98, 95% CI 0.97 to 0.99). Mild uniform DIF (p<0.001) was seen: two items showed better discrimination ability among men and two others among women.

CONCLUSIONS

The JSS showed overall good psychometric properties among this healthy population of employees in the Finnish public sector. The JSS was able to discriminate people with different severities of sleep disturbances. However, when using the JSS, the respondents might slightly underestimate the severity of these disturbances. While the JSS may produce slightly different results when answered by men and women, these sex-related differences are probably negligible when applied to clinical situations.

A systematic review of quality of life and health-related quality of life as outcomes in substance and behavioural addictions

ISSUES

Consideration of an individual's quality of life (QoL) can benefit assessment and treatment of addictive disorders, however, uncertainty remains over operationalisation of the construct as an outcome and the appropriateness of existing measures for these populations. This systematic review aimed to identify and evaluate QoL and health-related QoL outcome instruments used in addiction-related risk and harm research and map their conceptualised domains.

APPROACH

Three electronic databases and a specialised assessment library were searched on 1 February 2022 for QoL or health-related QoL outcome instruments used with addiction-related risk and harm populations. PRISMA reporting guidance was followed and included outcome instruments were appraised using mixed methods. Psychometric evidence supporting their use was summarised. The COSMIN risk of bias tool was used to assess validation studies.

KEY FINDINGS

A total of 298 articles (330 studies) used 53 outcome instruments and 41 unique domains of QoL. Eleven instruments' psychometric properties were evaluated. No instrument was assessed for any parameter in at least five studies for meta-analytic pooling. Cronbach's alpha (α) internal consistency was the most widely assessed parameter with the AQoLS, WHOQOL-BREF, ALQoL-9, Q-LES-Q-SF, SF-12, DUQoL, QLI and SF-36 displaying promising statistics (α > 0.70).

IMPLICATIONS AND CONCLUSION

Many instruments have been utilised. However, a significant proportion of studies applied a small number of instruments with minimal high-quality validation evidence supporting their use within addiction-related risk and harm. Promising instruments are recommended, however, the paucity of supporting evidence limits confidence in the reliability and validity of QoL measurement in these populations.

Validation of Generalized Anxiety Disorder 6 (GAD-6)-A Modified Structure of Screening for Anxiety in the Adolescent French Population

Anxiety disorders remain underdiagnosed and undertreated, especially in child and adolescent populations. This study aimed to examine the construct validity of the Generalized Anxiety Disorder Scale 7 (GAD-7) in a sample of French adolescents by combining the Classical Test Theory (CTT) and the Item Response Theory (IRT) and to assess the invariance of items. A total of 284 adolescents enrolled in school in the Lorraine region were randomly selected to participate in a cross-sectional study. A psychometric evaluation was performed using a combination of CTT and IRT analyses. The study of psychometric properties of GAD-7 revealed poor adequation to the sample population, and engendered the deletion of one item (#7) and the merger of two response modalities (#2 and #3). These modifications generated the new GAD-6 scale, which had a good internal consistency reliability (Cronbach α = 0.85; PSI = 0.83), acceptable goodness-of-fit indices (χ2 = 28.89, df = 9, P = 0.001; RMSEA (90% CI) = 0.088 [0.054; 0.125]; SRMR = 0.063; CFI = 0.857), and an acceptable convergent validity (r = -0.62). Only one item (#5) had a consistent Differential Item Functioning (DIF) by gender. This study evaluated the structure of the GAD-7 scale, which was essentially intended at discriminating adolescent patients with high levels of anxiety, and adapted it to a population of adolescents from the general population. The GAD-6 scale presents better psychometric properties in this general population than the original GAD-7 version.

Prevalence and Family Determinants of Geriatric Depression Among Elderly People in Elderly Support Groups in Rwanda

Background

The 1994 Tutsi genocide in Rwanda significantly impacted family structure, with many people growing old alone and lacking social bonds and connections with family members. However, little is known about the contribution of the family environment to geriatric depression which was highlighted by WHO as a psychological problem with a 10% to 20% prevalence rate among the elderly worldwide. This study aims to investigate geriatric depression and associated family determinants among the elderly in Rwanda.

Methods

With a community-based cross-sectional study design, we assessed geriatric depression (GD), quality-of-life enjoyment and satisfaction (QLES), family support (FS), loneliness, neglect, and attitude toward grief in a convenience sample of 107 participants (M=72.32, SD=8.79) aged between 60 and 95 years who were recruited from three groups of elderly people supported by the NSINDAGIZA organization in Rwanda. SPSS (version 24) was used for statistical data analysis; differences across various sociodemographic variables were tested for significance by an independent t-test; the relationship between study variables was tested by Pearson correlation analysis; and multiple regression analysis was performed to model the contribution of independent variables to dependent variables.

Results

A total of 64.5% of the elderly scored above the threshold of the normal range of geriatric depression (SDS>49), with higher symptoms in women than in men. Multiple regression analysis indicated that family support and quality-of-life enjoyment and satisfaction were contributors to geriatric depression in the participants.

Conclusion

Geriatric depression was relatively common in our participants. It is associated with the quality of life and family support received. Hence, adequate family-based interventions are needed to improve the well-being of geriatric people in their respective families.

Cross-cultural measurement invariance of the Quality of Life Enjoyment and Satisfaction Questionnaire-Short form across ten countries: the application of Bayesian approximate measurement invariance

Background

The Quality of Life Enjoyment and Satisfaction Questionnaire-Short Form (Q-LES-Q-SF) is the most frequently used generic quality of life (QOL) measure in many countries and cultures worldwide. However, no single study has been carried out to investigate whether this questionnaire performs similarly across diverse cultures/countries. Accordingly, this study aimed to assess the cross-cultural measurement invariance of the Q-LES-Q-SF across ten different countries.

Methods

The Q-LES-Q-SF was administrated to a sample of 2822 university students from ten countries: Bangladesh, Brazil, Croatia, India, Nepal, Poland, Serbia, Turkey, the United Arab Emirates, and Vietnam. The Bayesian approximate measurement invariance approach was used to assess the measurement invariance of the Q-LES-Q-SF.

Results

Approximate measurement invariance did not hold across the countries for the Q-LES-Q-SF, with only two out of 14 items being non-invariant; namely items related to doing household and leisure time activities.

Conclusions

Our findings did not support the cross-cultural measurement invariance of the Q-LES-Q-SF; thus, considerable caution is warranted when comparing QOL scores across different countries with this measure. Item rewording and adaptation along with calibrating non-invariant items may narrow these differences and help researchers to create an invariant questionnaire for reliable and valid QOL comparisons across different countries.

A comparison of methods to address item non-response when testing for differential item functioning in multidimensional patient-reported outcome measures

PURPOSE

Item non-response (i.e., missing data) may mask the detection of differential item functioning (DIF) in patient-reported outcome measures or result in biased DIF estimates. Non-response can be challenging to address in ordinal data. We investigated an unsupervised machine-learning method for ordinal item-level imputation and compared it with commonly-used item non-response methods when testing for DIF.

METHODS

Computer simulation and real-world data were used to assess several item non-response methods using the item response theory likelihood ratio test for DIF. The methods included: (a) list-wise deletion (LD), (b) half-mean imputation (HMI), (c) full information maximum likelihood (FIML), and (d) non-negative matrix factorization (NNMF), which adopts a machine-learning approach to impute missing values. Control of Type I error rates were evaluated using a liberal robustness criterion for α = 0.05 (i.e., 0.025-0.075). Statistical power was assessed with and without adoption of an item non-response method; differences > 10% were considered substantial.

RESULTS

Type I error rates for detecting DIF using LD, FIML and NNMF methods were controlled within the bounds of the robustness criterion for > 95% of simulation conditions, although the NNMF occasionally resulted in inflated rates. The HMI method always resulted in inflated error rates with 50% missing data. Differences in power to detect moderate DIF effects for LD, FIML and NNMF methods were substantial with 50% missing data and otherwise insubstantial.

CONCLUSION

The NNMF method demonstrated comparable performance to commonly-used non-response methods. This computationally-efficient method represents a promising approach to address item-level non-response when testing for DIF.

Poor Sleep Quality and Other Risk Factors for Unemployment Among Patients on Opioid Agonist Treatment

Purpose:

Patients with opioid use disorder (OUD) face high rates of unemployment, putting them at higher risk of treatment nonadherence and poor outcomes, including overdose death. The objective of this study was to investigate sleep quality and its association with other biopsychosocial risk factors for unemployment in patients receiving opioid agonist treatment (OAT) for OUD.

Methods:

Using a cross-sectional survey design, participants from 3 OAT programs for OUD completed questionnaires to measure sleep quality (Pittsburgh Sleep Quality Index [PSQI]); pain disability; catastrophic thinking; injustice experience; quality of life; and self-assessed disability. Spearman’s rank correlation was used to test for associations between sleep quality and other study variables.

Results:

Thirty-eight participants completed the study, with mean age 45.6 ± 10.9 years, 27 (71.1%) males, and 16 (42.1%) reporting a high school diploma/equivalent certification as the highest level of academic attainment. Poor sleep quality (defined as PSQI > 5) was identified in 29 participants (76.3%) and was positively correlated with pain disability (r = 0.657, P < .01), self-assessed disability (r = 0.640, P < .001), symptom catastrophizing (r = 0.499, P < .001), and injustice experience (r = 0.642, P < .001), and negatively correlated with quality of life (r = −0.623, P < .001).

Conclusions:

There was a high prevalence of poor sleep quality in patients with OUD on OAT and this was associated with multiple known risk factors for unemployment. These findings warrant the consideration of regular screening for sleep problems and the inclusion of sleep-related interventions to improve sleep quality, decrease the unemployment rate, and enhance the recovery process for individuals with OUD undergoing OAT.

The Hausa 12-item short-form health survey (SF-12): Translation, cross-cultural adaptation and validation in mixed urban and rural Nigerian populations with chronic low back pain

INTRODUCTION

Measuring health-related quality of life (HRQOL) in patients with chronic low back pain (LBP) is crucial to monitor and improve the patients' health status through effective rehabilitation. While the 12-item short-form health survey (SF-12) was developed as a shorter alternative to the 36-item short-form health survey for assessing HRQOL in large-scale studies, to date, no cross-culturally adapted and validated Hausa version exists. This study aimed to translate and cross-culturally adapt the SF-12 into Hausa language, and test its psychometric properties in mixed urban and rural Nigerian populations with chronic LBP.

METHODS

The Hausa version of the SF-12 was developed following the guidelines of the International Quality of Life Assessment project. Fifteen patients with chronic LBP recruited from urban and rural communities of Nigeria pre-tested the Hausa SF-12. A consecutive sample of 200 patients with chronic LBP recruited from urban and rural clinics of Nigeria completed the instrument, among which 100 respondents re-tested the instrument after two weeks. Factorial structure and invariance were assessed using confirmatory factor analysis (CFA) and multi-group CFA respectively. Multi-trait scaling analysis (for convergent and divergent validity) and known-groups validity were performed to assess construct validity. Composite reliability (CR), internal consistency (Cronbach's α), intraclass correlation coefficients (ICC), and Bland-Altman plots were computed to assess reliability.

RESULTS

After the CFA of the original conceptual SF-12 model, 2 redundant items were removed and 4 error terms were allowed to covary, thus providing adequate fit to the sample. The refined model demonstrated good fit and evidence of factorial invariance in three demographic groups (age, gender, and habitation). Convergent (11:12; 91% success rate) and divergent (10:12; 83% success rate) validity were satisfactory. Known-groups comparison showed that the instrument discriminated well for those who differed in age (p < 0.05) but in gender and habitation (p > 0.05). The physical component summary and the mental component summary demonstrated acceptable CR (0.69 and 0.79 respectively), internal consistency (α = 0.73 and 0.78 respectively), test-rest reliability (ICC = 0.79 and 0.85 respectively), and good agreement between test-retest values.

CONCLUSIONS

The Hausa SF-12 was successfully developed and showed evidence of factorial invariance across age, gender, and habitation. The instrument demonstrated satisfactory construct validity, internal consistency, and test-retest reliability. However, stronger psychometric properties need to be established in general population and other patients groups in future studies. The instrument can be used clinically and for research in Hausa-speaking patients with chronic LBP.

Challenges and lessons learned from using anchoring vignettes to explore quality of life response behavior

Purpose

Asking patients to rate health-related quality of life (HRQoL) of hypothetical individuals described in anchoring vignettes has been proposed to enhance knowledge on how patients understand and respond to HRQoL questionnaires. In this article, we describe the development of anchoring vignettes and explore their utility for measuring response shift in patients’ self-reports of HRQoL.

Methods

We conducted an explorative mixed-methods study. One hundred patients with multiple sclerosis or psoriasis participated in two interviews at intervals of 3–6 months. During both interviews, patients assessed HRQoL of 16 hypothetical individuals on the SF-12 questionnaire (two vignettes for each of the eight domains of the SF-12). In addition to these quantitative ratings, we used the think-aloud method to explore changes in patients’ verbalization of their decision processes during vignette ratings.

Results

Agreement of vignette ratings at baseline and follow-up was low (ICCs < 0.55). In addition, paired sample t-tests revealed no significant directional mean changes in vignette ratings. Thus, ratings changed non-directionally, neither confirming retest reliability nor a systematic change of assessment. Furthermore, patients’ verbalization of their decision processes did not indicate whether or not the assessment strategy of individual patients had changed.

Conclusions

Patients’ ratings of anchoring vignettes fluctuate non-directionally over time. The think-aloud method appears not to be informative in exploring whether these fluctuations are due to changes in the individual decision process. Overall, vignettes might not be an appropriate approach to explore response shift, at least with regard to the specific target population and the use of the SF-12.

Electronic supplementary material

The online version of this article (10.1007/s11136-020-02488-4) contains supplementary material, which is available to authorized users.

Patient's early satisfaction with care: a predictor of health-related quality of life change among outpatients with substance dependence

Background

Although research on health-related quality of life (HRQoL) has increased in the addiction field, few studies have focused on the determinants of HRQoL changes. This study aimed to describe dependent patients’ HRQoL changes at a 3-month follow-up and to assess whether satisfaction with care can predict those changes among outpatients starting care for alcohol or opioid dependence.

Methods

HRQoL was measured with the SF-12 at baseline and 3 months later in a prospective cohort of dependent outpatients. Satisfaction was assessed with the EQS-C early after inclusion. Data on sociodemographics, clinical characteristics and patients’ levels of anxiety and depression were also collected. A multivariable analysis was performed to identify factors associated with HRQoL changes in both the physical and mental component summary scores (PCS and MCS, respectively).

Results

Of the 172 patients included at baseline, a total of 136 patients assessed their satisfaction with care. The mean PCS and MCS scores were initially low, and HRQoL improvement was significant after 3 months for both the PCS and MCS. Never having been married (β = 5.5; p = 0.001) and a lower baseline PCS score (β = − 0.6; p < 0.0001) were associated with significant PCS improvement, whereas being legally compelled to undergo drug treatment (β = − 5.9; p = 0.02) was associated with less PCS change. Higher early satisfaction with care (β = 0.1; p = 0.02) and a lower baseline MCS score (β = − 0.7; p < 0.0001) were associated with significant MCS improvement.

Conclusion

The study supported the hypothesis that greater satisfaction with care may predict HRQoL improvement among dependent outpatients. Further studies are needed to understand the factors that affect patients’ early satisfaction to identify areas of improvement and thus improve HRQoL.

Distributional Regression Techniques in Socioeconomic Research on the Inequality of Health with an Application on the Relationship between Mental Health and Income

This study addresses the much-discussed issue of the relationship between health and income. In particular, it focuses on the relation between mental health and household income by using generalized additive models of location, scale and shape and thus employing a distributional perspective. Furthermore, this study aims to give guidelines to applied researchers interested in taking a distributional perspective on health inequalities. In our analysis we use cross-sectional data of the German socioeconomic Panel (SOEP). We find that when not only looking at the expected mental health score of an individual but also at other distributional aspects, like the risk of moderate and severe mental illness, that the relationship between income and mental health is much more pronounced. We thus show that taking a distributional perspective, can add to and indeed enrich the mostly mean-based assessment of existent health inequalities.

Differential item functioning of the SF-12 in a population-based regional joint replacement registry

Background

Joint replacement, an increasingly common procedure amongst older adults, can substantially improve health-related quality of life (HRQoL). However, differential item functioning (DIF) may affect the accurate interpretation of differences in HRQoL amongst patients with different demographic and health status characteristics but the same underlying (i.e., latent) level of the investigated construct. This study tested for DIF in pre-operative SF-12 physical health (PH) and mental health (MH) sub-scale items amongst patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA).

Methods

Data were from a population-based joint replacement registry from the Canadian province of Manitoba. TKA and THA patients who had surgery between 2009 and 2015 and completed a pre-operative assessment were included. DIF was tested using the multiple indicators multiple causes (MIMIC) method with sex, age group, body weight status, and presence of multiple comorbid conditions (i.e., multimorbidity) as covariates. Analyses were stratified by joint type.

Results

The study cohort included 8820 patients; 42.1% underwent THA, 57.3% were female, 32.7% were 70+ years, and 52.8% were obese. For each sub-scale, four of the six items exhibited DIF in both THA and TKA groups. Differences in the covariate effect estimates for DIF and No-DIF models on the MH latent variable were largest for age and body weight status for the THA group, and for sex and multimorbidity for the TKA group. All of the differences were small for PH. Multimorbidity had the strongest association with PH and age and sex had the strongest association with MH in the DIF models.

Conclusions

Demographic and health status characteristics influenced SF-12 PH and MH item responses in joint replacement populations, although the size of the effects were not large for PH. We recommend testing and adjusting for DIF effects to ensure comparability of HRQoL measures in joint replacement populations.

Electronic supplementary material

The online version of this article (10.1186/s12955-019-1166-1) contains supplementary material, which is available to authorized users.

Migraine-Specific Quality of Life Questionnaire Chinese version 2.1 (MSQv2.1-C): psychometric evaluation in patients with migraine

BACKGROUND

Migraine ranks as the third most prevalent disease and the seventh most common cause of disability worldwide. To better understand the impact of migraine on the quality of life of individuals with this diagnosis, and how these might differ from one country or culture to another, reliable and valid measures of quality of life that are available in different languages are needed. To address this need, here we (1) translated the Migraine-Specific Quality of Life Questionnaire into Chinese (MSQv2.1-C), and (2) examined the psychometric properties of the measure.

METHODS

Forward and backward translation was conducted using four bilingual experts. One native speaker finalized the translation. Cognitive testing was performed by interviewing 11 monolingual migraineurs, and modifications were made to the MSQv2.1-C, as appropriate. Next, 174 individuals with a history of migraine completed the MSQv2.1-C, along with the SF-12, Migraine Disability Assessment Scale, and numerical rating scale s assessing pain intensity. We then evaluated the reliability and validity of the MSQv2.1-C by performing analyses to evaluate its internal consistency, test-retest reliability, convergent validity, criterion validity, and construct validity.

RESULTS

The MSQv2.1-C scales demonstrated (1) good internal consistency (Cronbach's alpha s ≥ 0.81); (2) good 1-week test-retest reliability (intra-class coefficients ≥0.69 and Spearman's rho correlation coefficients ≥0.74); (3) convergent validity (positive correlations with the MSQ and SF-12 scales [rho range = 0.27 to 0.37, ps < 0.05]); (4) criterion validity (negative correlations [rho range = - 0.51 to - 0.25, ps < 0.05]) between the MSQv2.1-C scales and pain-related criterion variables; and (5) construct validity (item factor loadings ranging from 0.71 to 0.96 [> 0.5]).

CONCLUSIONS

The MSQv2.1-C exhibited satisfactory reliability and validity in a sample of individuals with migraine who speak Chinese. The availability of this measure will facilitate research, including cross-cultural research, on the quality of life of individuals with migraine.

Identification of Factors Affecting the Quality of Life Among Patients With Addiction in Lebanon

Our objective was to assess factors associated with the physical (Short-Form 12-physical component summary [SF-12-PCS]) and mental (Short-Form 12-mental component summary [SF-12-MCS]) quality of life (QOL) in the Lebanese population. A cross-sectional study, conducted between July and September 2017, enrolled 57 patients with substance use disorder from the Psychiatric Hospital of the Cross. The SF-12 scale was used to assess the QOL among participants. A first stepwise linear regression, using the SF-12-PCS score as the dependent variable, showed that females compared with males (β = -4.86) and having a family history of substance use disorder (β = -4.70) were associated with lower physical QOL (lower SF-12-PCS scores). A second stepwise linear regression, using the SF-12-MCS score as the dependent variable, showed that having a generalized anxiety disorder (β = -10.52) and having suicidal ideation (β = -8.05) were associated with lower mental QOL (lower SF-12-MCS scores). Strategic interventions are needed to manage the health-related QOL in those with substance abuse.

Factor structure of the Q-LES-Q short form in an enrolled mental health clinic population

PURPOSE

The Quality of Life, Enjoyment, and Satisfaction Questionnaire-Short Form (Q-LES-Q-SF) is a recovery-oriented, self-report measure with an uncertain underlying factor structure, variously reported in the literature to consist of either one or two domains. We examined the possible factor structures of the English version in an enrolled mental health population who were not necessarily actively engaged in care.

METHODS

As part of an implementation trial in the U.S. Department of Veterans Affairs mental health clinics, we administered the Q-LES-Q-SF and Veterans RAND 12-Item Health Survey (VR-12) over the phone to 576 patients across nine medical centers. We used a split-sample approach and conducted an exploratory factor analysis (EFA) and multi-trait analysis (MTA). Comparison with VR-12 assessed construct validity.

RESULTS

Based on 568 surveys after excluding the work satisfaction item due to high unemployment rate, the EFA indicated a unidimensional structure. The MTA showed a single factor: ten items loaded on one strong psychosocial factor (α = 0.87). Only three items loaded on a physical factor (α = 0.63). Item discriminant validity was strong at 92.3%. Correlations with the VR-12 were consistent with the existence of two factors.

CONCLUSIONS

The English version of the Q-LES-Q-SF is a valid, reliable self-report instrument for assessing quality of life. Its factor structure can be best described as one strong psychosocial factor. Differences in underlying factor structure across studies may be due to limitations in using EFA on Likert scales, language, culture, locus of participant recruitment, disease burden, and mode of administration.

Measurement invariance of the SF-12 among different demographic groups: The HELIUS study

AIM

To investigate whether items of the SF-12, widely used to assess health outcome in clinical practice and public health research, provide unbiased measurements of underlying constructs in different demographic groups regarding gender, age, educational level and ethnicity.

METHODS

We included 23,146 men and women aged 18-70 of Dutch, South-Asian Surinamese, African Surinamese, Ghanaian, Turkish, or Moroccan origin from the HELIUS study. Both multiple group confirmatory factor analyses (MGCFA), with increasingly stringent model constraints (i.e. assessing Configural, Metric, Strong and Strict measurement invariance (MI)), and regression analysis were conducted to establish comparability of SF-12 items across demographic groups.

RESULTS

MI regarding gender, age and education was tested in the ethnic Dutch group (N = 4,615). In each subsequent step of testing MI, change in goodness-of-fit measures did not exceed 0.010 (RMSEA) or 0.004 (CFI). Moreover, goodness-of-fit indices showed good fit for strict invariance models: RMSEA<0.055; CFI>0.97. Regarding ethnicity, RMSEA values of metric and subsequent models fell above 0.055, indicating violation of measurement invariance in factor loadings, thresholds and residual variances. Regression analysis revealed possible age-, education- and ethnicity-related DIF. Adjustment for this DIF had little impact on the magnitude of age and educational differences in physical and mental health, but ethnic inequalities in physical health-and to a lesser extent mental health-were reduced after DIF adjustment.

CONCLUSIONS

We found no evidence of violation of measurement invariance of the SF-12 regarding gender, age and educational level. If minor DIF would remain undetected in our MGCFA analyses, we showed that this would have negligible effect on the magnitude of demographic health inequalities. Regarding ethnicity, the SF-12 was not measurement invariant. After accounting for DIF, we observed a reduction of ethnic inequalities in health, in particular in physical health. Caution is warranted when comparing SF-12 scores across population groups with various ethnic backgrounds.

Acupoint herbal plaster for patients with primary dysmenorrhea: study protocol for a randomized controlled trial

BACKGROUND

Primary dysmenorrhea (PD), is one of main gynecological complaints in women of child-bearing age. Common medications for PD do not always achieve satisfactory outcome of pain relief. Hence, both health professionals and patients are seeking help from complementary and alternative medicine. The acupoint herbal plaster (AHP), which appears to be a safe and effective way to alleviate menstrual pain, as well as to improve other PD-related symptoms. Despite similar clinical studies for this condition in the past, no high-quality methodology-based clinical trial has been reported to date. The current study aims to assess the efficacy of the AHP compared with the acupoint placebo plaster (APP) and being placed on a waiting-list control group in patients with primary dysmenorrhea.

METHODS/DESIGN

This study is a randomized, single-center, placebo-controlled clinical trial. A total of 180 women with PD will be included and randomly allocated to the AHP, APP and waiting-list (WL) groups in a 1:1:1 ratio. Patients in the AHP group will be provided with herbal plasters (Shaofuzhuyu decoction) on various acupoints: Shenque (CV8), Guanyuan (CV4), Qihai (CV5), Ciliao (BL32) and Zigong (EX-CA1). Women in the APP group will receive placebo plasters on the same acupoints, and no intervention will be given to the WL group until completion of the study. The primary outcome will be pain intensity reduction measured by a Visual Analog Scale (VAS), with other outcome measurements including the Cox Menstrual Symptom Scale (CMSS), the 12-Item Short Form Health Survey (SF-12) and the Participant Global Impression of Change (PGIC). All assessments will be performed at baseline, each menstrual cycle during the treatment course and the follow-up course. Any adverse events will be recorded throughout the study.

DISCUSSION

This is the first study to compare the changes in menstrual pain after three different interventions: the active intervention (AHP), the placebo intervention (APP), and a period of no intervention (WL). This three-arm randomized controlled trial (RCT) aims to investigate the relative contributions of the specific (AHP vs. APP) and non-specific (APP vs. WL) effects to the overall clinical effects of the active AHP on women with PDM. The scientific and rigorous methodology design of this trial should gather good evidence to assess the curative effects and safety of the AHP on PD. Moreover, the results of this study may provide evidence-based references for the treatment of menstrual pain in future.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ID: ChiCTR-TRC-16008701. Registered on 22 July 2016.

Reconsidering the income-health relationship using distributional regression

We reconsider the relationship between income and health taking a distributional perspective rather than one centered on conditional expectation. Using structured additive distributional regression, we find that the association between income and health is larger than generally estimated because aspects of the conditional health distribution that go beyond the expectation imply worse outcomes for those with lower incomes. Looking at German data from the Socio-Economic Panel, we find that the risk of bad health is roughly halved when doubling the net equivalent income from 15,000 to 30,000€. This is more than tenfold of the magnitude of change found when considering expected health measures. A distributional perspective thus highlights another dimension of the income-health relation-that the poor are in particular faced with greater health risk at the lower end of the health distribution. We therefore argue that when studying health outcomes, a distributional approach that considers stochastic variation among observationally equivalent individuals is warranted.

Examining gender-related differential item functioning of the Veterans Rand 12-item Health Survey

PURPOSE

Previous research suggests that gender differences in patient-reported outcome measures (PROMs) may reflect measurement bias rather than true differences in underlying health status. The aim of this study is to examine whether the Veterans Rand 12-item Health Survey (VR-12) allows for unbiased comparisons of physical and mental health scores across gender. The VR-12 is a generic PROM consisting of 12 items with 3-6 response options for the measurement of mental and physical health.

METHODS

Study data were from the 2015 Health Outcomes Survey pertaining to the Medicare beneficiaries. A total of 277,518 participants included 116,817 (42.1%) males and 160,701 (57.9%) females. Scale-level and item-level differential functioning methods were applied using multiple-group confirmatory factor analysis and ordinal logistic regression, respectively.

RESULTS

The scale-level differential functioning showed support for strict invariance (RMSEA = 0.045; CFI = 0.995) across gender. Although we found statistically significant differential item functioning for several items, the magnitude was negligible (maximum ΔR ² = 0.007).

CONCLUSION

The VR-12 physical and mental health status scores are unbiased with respect to gender.

Quality of Life Perspectives of People With Amyotrophic Lateral Sclerosis and Their Caregivers

This study explored differences in perspectives on quality of life (QOL) between people affected by amyotrophic lateral sclerosis (ALS) and their caregivers. QOL is often thought of as related to physical limitations, without consideration of other factors (e.g., cognitive, emotional) that may be stronger predictors of QOL in people with long-term degenerative diseases. Because QOL is complex and influenced by multiple factors, people with ALS and their caregivers may have different perspectives on what constitutes QOL. This study investigated potential discrepancies in QOL perspectives between people with ALS and their caregivers. Thirty dyads from the Augusta University Health ALS Clinic completed a measure of QOL, and we compared the results and identified patterns. The most prominent finding was that members of the dyads misunderstood the mental experiences of one another.

The effects of patient and physician characteristics on early outpatient satisfaction with substance dependence care: results of the SUBUSQOL study

BACKGROUND

Although patient perceptions of health care have increasingly been explored in the literature, little is known about care satisfaction among individuals with substance dependence. This exploratory study assessed the relationships between patient and physician characteristics and early outpatient satisfaction with care for alcohol and opioid dependence.

METHODS

Satisfaction was assessed using a multidimensional, self-administered and validated questionnaire during the early care process among a prospective outpatient cohort. In addition to measuring satisfaction and obtaining sociodemographic and clinical data, this study collected data on the self-reported health status and physician characteristics at inclusion. Cross-sectional analysis with multiple linear regression was performed to identify the variables associated with satisfaction level.

RESULTS

A total of 249 outpatients were included, and 63.8% completed the satisfaction questionnaire. Patients without a history of previous care for substance dependence were more satisfied with the appointment-making process (β=7.2; P=0.029) and with the doctor consultation (β=10.3; P=0.003) than those who had received care previously. Neither sociodemographic characteristics nor self-reported health status was associated with outpatient satisfaction.

CONCLUSION

The factors that affect patients' ratings of early satisfaction with the care that they receive should be studied further because increased understanding of the factors that negatively affect these ratings might enable caregivers and outpatient management facilities to improve the patient experience during the early stages of care, which might in turn improve treatment adherence, continuity of care, and other health-related outcomes.