Infant sugar sweetened beverage and 100% juice consumption: Racial/ethnic differences and links with fathers' consumption in a longitudinal cohort.

The consumption of sugar-sweetened beverages (SSB) and 100% juice before age 12 months is discouraged. We examine racial/ethnic differences in SSB and 100% juice consumption when infants were 6- and 12-months old and examine links between fathers' and infants' beverage consumption. Participants were from a longitudinal cohort of infants and their parents (recruited 2016-2018), followed from birth until the child was 24 months. In 2020, we analyzed data collected when infants were 6- (N = 352 infants and 168 fathers) and 12-months (N = 340 infants and 152 fathers) old. Based on maternal report, 13% of infants consumed 100% juice at 6 months and 31% at 12 months. Two percent of infants consumed SSB at 6 months and 7% at 12 months. In models adjusting for income and education, Black/African American (Black/AA) and Hispanic infants were 5-6 times as likely at 6 months and 3 times as likely at 12 months to consume 100% juice compared with non-Hispanic white and Asian infants. At 12 months, Black/AA and Hispanic infants were 6-7 times as likely to consume SSB than non-Hispanic white and Asian infants after adjusting for covariates. In unadjusted models, infants were more likely to consume 100% juice and SSB at 12 months when their fathers were high consumers (>12times/month) of the beverage; effects were no longer significant after adjusting for income, race/ethnicity, education and maternal beverage consumption. Results highlight the need to implement culturally responsive interventions promoting healthy beverage consumption in infants prior to birth and should concurrently target fathers, in addition to mothers.

Nutrition, Immigration and Health Determinants Are Linked to Verbal Fluency among Anglophone Adults in the Canadian Longitudinal Study on Aging (CLSA).

OBJECTIVES: Later-life cognitive impairment is an important health issue; however, little is known about the condition among diverse groups such as immigrants. This study aims to examine whether the healthy immigrant effect exists for verbal fluency, an indicator of cognitive functioning, among anglophone middle-aged and older adults in Canada. METHODS: Using from the baseline data of the Canadian Longitudinal Study on Aging (CLSA), multiple linear regression was employed to compare associations among immigrants (recent and long-term) and Canadian-born residents without dementia for two verbal fluency tests, the Controlled Oral Word Association Test (COWAT) and the Animal Fluency (AF) task. Covariates included socioeconomic, physical health, and dietary intake. RESULTS: Of 8,574 anglophone participants (85.7% Canada-born, 74.8% aged 45-65 years, 81.8% married, 81.9% with a post-secondary degree), long-term immigrants (settled in Canada >20 years) performed significantly better than Canadian-born residents for the COWAT (42.8 vs 40.9) but not the AF task (22.4 vs 22.4). Results of the multivariable adjusted regression analyses showed that long-term immigrants performed better than Canadian-born peers in both the COWAT (B=1.57, 95% CI: 0.80-2.34) and the AF test (B=0.57, 95% CI: 0.19-0.95), but this advantage was not observed among recent immigrants. Other factors associated with low verbal fluency performance included being single, socioeconomically disadvantaged, having hypertension, excess body fat, and consuming low amounts of pulses/nuts or fruit/vegetables. CONCLUSIONS: Long-term immigrants had higher verbal fluency test scores than their Canadian-born counterparts. Immigration status, social, health and nutritional factors are important considerations for possible intervention and prevention strategies for cognitive impairment.

Testing a theoretical model of imminent fracture risk in elderly women: an observational cohort analysis of the Canadian Multicentre Osteoporosis Study.

We examined the underlying relationship between fracture risk factors and their imminent risk. Results suggested that having past year fracture, worse past year general health, worse past year physical functioning, and lower past year BMD T-score directly predicted higher imminent fracture risk. Past year falls indirectly predicted imminent risk through physical functioning and general health. INTRODUCTION: This study aimed to examine direct and indirect effects of several factors on imminent (1 year) fracture risk. METHODS: Data from women age 65 and older from population-based Canadian Multicentre Osteoporosis Study were used. Predictors were identified from study years 5 and 10, and imminent fracture data (1-year fracture) came from years 6 and 11 (year 5 predicts year 6, year 10 predicts year 11). A structural equation model (SEM) was used to test the theoretical construct. General health and physical functioning were measured as latent variables using items from the 36-Item Short Form Health Survey (SF-36) and bone mineral density (BMD) T-score was a latent variable based on observed site-specific BMD data (spine L1-L4, femoral neck, total hip). Observed variables were fractures and falls. Model fit was evaluated using root mean square error of approximation (RMSEA), Tucker Lewis index (TLI), and comparative fit index (CFI). RESULTS: The analysis included 3298 women. Model fit tests showed that the SEM fit the data well; χ2(172) = 1122.10 < .001, RMSEA = .03, TLI = .99, CFI = .99. Results suggested that having past year fracture, worse past year general health, worse past year physical functioning, and lower past year BMD T-score directly predicted higher risk of fracture in the subsequent year (p < .001). Past year falls had a statistically significant but indirect effect on imminent fracture risk through physical functioning and general health (p < .001). CONCLUSIONS: We found several direct and indirect pathways that predicted imminent fracture risk in elderly women. Future studies should extend this work by developing risk scoring methods and defining imminent risk thresholds.

Combining Frailty and Trabecular Bone Score Did Not Improve Predictive Accuracy in Risk of Major Osteoporotic Fractures.

It is recognized that the trabecular bone score (TBS) provides skeletal information, and frailty measurement is significantly associated with increased risks of adverse health outcomes. Given the suboptimal predictive power in fracture risk assessment tools, we aimed to evaluate the combination of frailty and TBS regarding predictive accuracy for risk of major osteoporotic fracture (MOF). Data from the prospective longitudinal study of CaMos (Canadian Multicentre Osteoporosis Study) were used for this study. TBS values were estimated using lumbar spine (L1 to L4 ) dual-energy X-ray absorptiometry (DXA) images; frailty was evaluated by a frailty index (FI) of deficit accumulation. Outcome was time to first incident MOF during the follow-up. We used the Harrell's C-index to compare the model predictive accuracy. The Akaike information criterion, likelihood ratio test, and net reclassification improvement (NRI) were used to compare model performances between the model combining frailty and TBS (subsequently called "FI + TBS"), FI-alone, and TBS-alone models. We included 2730 participants (mean age 69 years; 70% women) for analyses (mean follow-up 7.5 years). There were 243 (8.90%) MOFs observed during follow-up. Participants with MOF had significantly higher FI (0.24 versus 0.20) and lower TBS (1.231 versus 1.285) than those without MOF. FI and TBS were significantly related with MOF risk in the model adjusted for FRAX with bone mineral density (BMD) and other covariates: hazard ratio (HR) = 1.26 (95% confidence interval [CI] 1.11-1.43) for per-SD increase in FI; HR = 1.38 (95% CI 1.21-1.59) for per-SD decrease in TBS; and these associations showed negligible attenuation (HR = 1.24 for per-SD increase in FI, and 1.35 for per-SD decrease in TBS) when combined in the same model. Although the model FI + TBS was a better fit to the data than FI-alone and TBS-alone, only minimal and nonsignificant enhancement of discrimination and NRI were observed in FI + TBS. To conclude, frailty and TBS are significantly and independently related to MOF risk. Larger studies are warranted to determine whether combining frailty and TBS can yield improved predictive accuracy for MOF risk. © 2020 American Society for Bone and Mineral Research.

Change in Quantitative Ultrasound-assessed Speed of Sound as a Function of Age in Women and Men and Association With the Use of Antiresorptive Agents: The Canadian Multicentre Osteoporosis Study.

INTRODUCTION: Five-year changes in multisite quantitative ultrasound-assessed speed of sound (SOS in m/s) were studied in a cohort of women and men. The impacts of antiresorptive therapies and menopausal status on SOS were also assessed. METHODOLOGY: Two SOS assessments, clinical assessments, and comprehensive questionnaires were completed 5 years apart on 509 women and 211 men. Age at first assessment was grouped into: <40 yr, 40-49 yr, 50-59 yr, 60-69 yr, 70-79 yr and 80+ yr. Mean rate of change in SOS at the distal radius and tibia were calculated for each age grouping by sex. SOS changes were stratified by antiresorptive use (yes, no) or menopausal status (premenopausal, postmenopausal, or bilateral oophorectomy). RESULTS: Mean losses in SOS occurred over the 5 years in almost all age groupings. In women, mean losses in SOS for the <40 yr, 40-49 yr, 50-59 yr, 60-69 yr, 70-79 yr, and 80+ yr age groupings were -59, -83, -107, -92, -80 and -66 (p = 0.30; differences among age groupings) at the radius and -18, -16, -54, -1, -9 and 31 at the tibia (p < 0.05), respectively. In men, mean SOS losses were -101, -56, -69, -67, -83 and -127 at the radius (p = 0.61) and -46, -61, 0, -35, -29, and -26 at the tibia (p = 0.23). At the tibia, women prescribed antiresorptives had a mean increase in SOS (8.6 m/s) whereas untreated participants had a mean loss (-23.0; p < 0.001); there was no significant impact at the distal radius. There were no significant differences in change in SOS among menopausal groups (p > 0.26). CONCLUSIONS: Mean SOS generally declined over 5 years in all age groupings of both sexes. The consistent mean losses in SOS over the age spans investigated are coincident with increasing fracture risk. Women on antiresorptive therapy had increased mean SOS over the 5-year assessment period at the tibia, whereas untreated women had mean losses in SOS.

Western Osteoporosis Alliance Clinical Practice Series: Treat-to-Target for Osteoporosis.

Patients often start treatment to reduce fracture risk because of a bone mineral density T-score consistent with osteoporosis (≤ -2.5). Others with a T-score above -2.5 may be treated when there is a history of fragility fracture or when a fracture risk algorithm categorizes them as having a high risk for fracture. It is common to initiate therapy with a generic oral bisphosphonate, unless contraindicated, and continue therapy if the patient is responding as assessed by stability or an increase in bone mineral density. However, some patients may respond well to an oral bisphosphonate, yet remain with an unacceptably high risk for fracture. Recognition of this occurrence has led to the development of an alternative strategy: treat-to-target. This involves identifying a biological marker (treatment target) that represents an acceptable fracture risk and then initiating treatment with an agent likely to reach this target. If the patient is on a path to reaching the target with initial therapy, treatment is continued. If it appears the target will not be reached with initial therapy, treatment is changed to an agent more likely to achieve the goal.

Predictors of imminent non-vertebral fracture in elderly women with osteoporosis, low bone mass, or a history of fracture, based on data from the population-based Canadian Multicentre Osteoporosis Study (CaMos).

Using data from the Canadian Multicentre Osteoporosis Study, several risk factors predictive of imminent (2-year) risk of low-trauma non-vertebral fracture among high-risk women were identified, including history of falls, history of low-trauma fracture, poorer physical function, and lower T score. Careful consideration should be given to targeting this population for therapy. PURPOSE: Fracture risk assessment has focused on a long-term horizon and populations with a broad risk range. For elderly women with osteoporosis or low bone mass, or a history of fragility fractures ("high-risk women"), risk prediction over a shorter horizon may have greater clinical relevance. METHODS: A repeated-observations design and data from the Canadian Multicentre Osteoporosis Study were employed. Study population comprised women aged ≥ 65 years with T score (total hip, femoral neck, spine) ≤ - 1.0 or prior fracture. Hazard ratios (HR) for predictors of low-trauma non-vertebral fracture during 2-year follow-up were estimated using multivariable shared frailty model. RESULTS: The study population included 3228 women who contributed 5004 observations; 4.8% experienced low-trauma non-vertebral fracture during the 2-year follow-up. In bivariate analyses, important risk factors included age, back pain, history of falls, history of low-trauma fracture, physical function, health status, and total hip T score. In multivariable analyses, only four independent predictors were identified: falls in past 12 months (≥ 2 falls: HR = 1.9; 1 fall: HR = 1.5), low-trauma fracture in past 12 months (≥ 1 fracture: HR = 1.7), SF-36 physical component summary score (≤ 42.0: HR = 1.6), and total hip T score (≤ - 3.5: HR = 3.7; > - 3.5 to ≤ - 2.5: HR = 2.5; > - 2.5 to ≤ - 1: HR = 1.3). CONCLUSIONS: Imminent risk of low-trauma non-vertebral fracture is elevated among high-risk women with a history of falls or low-trauma fracture, poorer physical function, and lower T score. Careful consideration should be given to identifying and targeting this population for therapy.

Parity and lactation are not associated with incident fragility fractures or radiographic vertebral fractures over 16 years of follow-up: Canadian Multicentre Osteoporosis Study (CaMos).

Parity and lactation showed no associations with incident clinical fragility fractures or radiographic vertebral compression fractures in the 16-year CaMos prospective study. Parity was associated with slightly greater decline in femoral neck but not hip or spine areal bone mineral density (aBMD), while lactation showed no associations with aBMD change. PURPOSE: Pregnancy and especially lactation cause loss of bone mass and microarchitectural changes, which temporarily increase fracture risk. After weaning, aBMD increases but skeletal microarchitecture may be incompletely restored. Most retrospective clinical studies found neutral or even protective associations of parity and lactation with fragility fractures, but prospective data are sparse. CaMos is a randomly selected observational cohort that includes ~ 6500 women followed prospectively for over 16 years. METHODS: We determined whether parity or lactation were related to incident clinical fragility fractures over 16 years, radiographic (morphometric and morphologic) vertebral fractures over 10 years, and aBMD change (spine, total hip, and femoral neck) over 10 years. Parity and lactation duration were analyzed as continuous variables in predicting these outcomes using univariate and multivariate regression analyses. RESULTS: Three thousand four hundred thirty-seven women completed 16 years of follow-up for incident clinical fractures, 3839 completed 10 years of morphometric vertebral fracture assessment, 3788 completed 10 years of morphologic vertebral fracture assessment, and 4464 completed 10 years of follow-up for change in aBMD. In the multivariate analyses, parity and lactation duration showed no associations with clinical fragility fractures, radiographic vertebral fractures, or change in aBMD, except that parity associated with a probable chance finding of a slightly greater decline in femoral neck aBMD. CONCLUSIONS: Parity and lactation have no adverse associations with clinical fragility or radiographic vertebral fractures, or the rate of BMD decline over 10 years, in this prospective, multicenter study of a randomly selected, population-based cohort of women.

Safe supplies: few infections in UK blood and tissue donors.

AIMS/OBJECTIVES: Here, we describe the annual review of the UK blood services' infection surveillance schemes for 2017 (www.gov.uk/government/publications/safe-supplies-annual-review). BACKGROUND: The joint NHS Blood and Transplant/Public Health England Epidemiology Unit was set up in 1995 to ensure that blood and tissue safety is maintained, inform donor selection and testing policy and add to public health knowledge. METHODS: Several surveillance schemes for blood, tissues and bacterial screening collect the numbers of donations tested, reactive and confirmed positive in order to monitor trends in infection rates in donors and calculate residual risk of infection. Investigations of potential transfusion transmissions in recipients are also monitored. RESULTS: In the UK in 2017, the risk of testing not detecting a potentially infectious hepatitis B virus or hepatitis C virus or HIV donation was estimated as less than one in two million donations. One hepatitis A virus and one hepatitis E virus transmission incidents were proven to be transfusion-transmitted by unscreened donations. CONCLUSIONS: The Safe Supplies annual review provides a clear picture of the very low risk associated with blood and tissues in the UK nowadays. In November 2017, the blood services for England, Wales and Scotland implemented recommendations to reduce the deferrals for higher risk sexual behaviour from 12 to 3 months. The surveillance schemes are adapted to remain fit for purpose as testing and donor selection change.

Frailty and Risk of Fractures in Patients With Type 2 Diabetes.

OBJECTIVE: We aimed to explore whether frailty was associated with fracture risk and whether frailty could modify the propensity of type 2 diabetes toward increased risk of fractures. RESEARCH DESIGN AND METHODS: Data were from a prospective cohort study. Our primary outcome was time to the first incident clinical fragility fracture; secondary outcomes included time to hip fracture and to clinical spine fracture. Frailty status was measured by a Frailty Index (FI) of deficit accumulation. The Cox model incorporating an interaction term (frailty × diabetes) was used for analyses. RESULTS: The analysis included 3,149 (70% women) participants; 138 (60% women) had diabetes. Higher bone mineral density and FI were observed in participants with diabetes compared with control subjects. A significant relationship between the FI and the risk of incident fragility fractures was found, with a hazard ratio (HR) of 1.02 (95% CI 1.01-1.03) and 1.19 (95% CI 1.10-1.33) for per-0.01 and per-0.10 FI increase, respectively. The interaction was also statistically significant (P = 0.018). The HR for per-0.1 increase in the FI was 1.33 for participants with diabetes and 1.19 for those without diabetes if combining the estimate for the FI itself with the estimate from the interaction term. No evidence of interaction between frailty and diabetes was found for risk of hip and clinical spine fractures. CONCLUSIONS: Participants with type 2 diabetes were significantly frailer than individuals without diabetes. Frailty increases the risk of fragility fracture and enhances the effect of diabetes on fragility fractures. Particular attention should be paid to diabetes as a risk factor for fragility fractures in those who are frail.

Adult Premenopausal Bone Health Related to Reproductive Characteristics-Population-Based Data from the Canadian Multicentre Osteoporosis Study (CaMos).

Amenorrhea is important for women's bone health. However, few have reported reproductive, anthropometric (body mass index [BMI], height) and bone health (areal bone mineral density [BMD], prevalent fractures) in a population-based study. The purposes of this cross-sectional study of women in the randomly-selected Canadian Multicentre Osteoporosis Study (CaMos) population were: (1) to describe reproductive, demographic, anthropometric and lifestyle variables; and (2) in menstruating women, to relate reproductive and other variables to BMD at the lumbar spine (L1-4, LS), femoral neck (FN) and total hip (TH) sites and to prevalent fragility fractures. This study describes the reproductive characteristics of 1532 women aged 30⁻60 years. BMD relationships with reproductive and other variables were described in the 499 menstruating women. Mean menarche age was 12.8 years, 96% of women were parous and 95% had used combined hormonal contraceptives (CHC). Infertility was reported by 9%, androgen excess by 13%, amenorrhea by 8% and nulliparity by 4%. LS BMD was negatively associated with amenorrhea and androgen excess and positively related to current BMI and height. A later age at menarche negatively related to FN BMD. BMI and height were strongly related to BMD at all sites. Prevalent fragility fractures were significantly associated with quartiles of both LS and TH BMD.

The forgotten parent: Fathers' representation in family interventions to prevent childhood obesity.

Despite recognition that parents are critical stakeholders in childhood obesity prevention, obesity research has overwhelmingly focused on mothers. In a recent review, fathers represented only 17% of parent participants in >600 observational studies on parenting and childhood obesity. The current study examined the representation of fathers in family interventions to prevent childhood obesity and characteristics of interventions that include fathers compared with those that only include mothers. Eligible studies included family-based interventions for childhood obesity prevention published between 2008 and 2015 identified in a recent systematic review. Data on intervention characteristics were extracted from the original review. Using a standardized coding scheme, these data were augmented with new data on the number of participating fathers/male caregivers and mothers/female caregivers. Out of 85 eligible interventions, 31 (37%) included mothers and fathers, 29 (34%) included only mothers, 1 (1%) included only fathers, and 24 (28%) did not provide information on parent gender. Of the interventions that included fathers, half included 10 or fewer fathers. Across all interventions, fathers represented a mere 6% of parent participants. Father inclusion was more common in interventions targeting families with elementary school-aged children (6-10 years) and those grounded in Ecological Systems Theory, and was less common in interventions focused on very young children (0-1 years) or the prenatal period and those targeting the sleep environment. This study emphasizes the lack of fathers in childhood obesity interventions and highlights a particular need to recruit and engage fathers of young children in prevention efforts.

Development and preliminary validation of the Parenting around SNAcking Questionnaire (P-SNAQ).

Snacking makes significant contributions to children's dietary intake but is poorly understood from a parenting perspective. This research was designed to develop and evaluate the psychometrics of a theoretically grounded, empirically-informed measure of snack parenting. The Parenting around SNAcking Questionnaire (P-SNAQ) was developed using a conceptual model derived from current theory and mixed-methods research to include 20 hypothesized snack parenting practices along 4 parenting dimensions (autonomy support, structure, coercive control and permissiveness). Expert panel evaluation and cognitive interviews were used to refine items and construct definitions. The initial instrument of 105 items was administered to an ethnically diverse, low-income sample of 305 parents (92% mothers) of children aged 1-6 y participating in three existing cohort studies. The sample was randomly split into two equal samples. Exploratory factor analysis was conducted with the first sample to identify snack parenting practices within each parenting dimension, followed by confirmatory factor analysis with the second sample to test the hypothesized factor structure. Internal consistency of sub-scales and associations with existing measures of food parenting practices and styles and child weight status were evaluated. The final P-SNAQ scale included 51 items reflecting 14 snack parenting practices across four parenting dimensions. The factor structure of the P-SNAQ was consistent with prior theoretical frameworks. Internal consistency coefficients were good to very good for 12 out of 14 scales and subscale scores were moderately correlated with previously validated measures. In conclusion, initial evidence suggests that P-SNAQ is a psychometrically sound measure for evaluating a wide range of snack parenting practices in young children.

Dissecting the decline of hepatitis C in first-time donors in England and Wales.

BACKGROUND AND OBJECTIVES: The rate of confirmed hepatitis C virus (HCV) cases, in first-time donors, is much lower in 2015 than 20 years ago. We investigate reasons for the decline. MATERIALS AND METHODS: HCV rates were analysed by gender and birth cohort for 1996 to 2015 and ethnic group for 2006 to 2015. Variables for confirmed positive cases were compared for two ten-year periods (1996 to 2005 and 2006 to 2015) including genotyping data for 2006 to 2015. RESULTS: There were 2007 confirmed HCV cases identified between 1996 and 2015. The rate per 100 000 donations fell from 78·6 in 1996 to 26·9 by 2015. By birth cohort, HCV rates were highest in donors born in the 1950s and 1960s who contributed a decreasing proportion of first-time donors. Between 2006 and 2015, there was no significant decline in HCV rate. The HCV-positive donor profile has changed in the last 10 years with increased proportions of younger donors, donors born abroad and decreased reported injecting drug use. Genotype 1a remains predominate, but genotype 1b has increased associated with this change in birth cohort and ethnicity. CONCLUSION: The decline in number and rate of confirmed HCV-positive first-time donors is mainly due to a decrease in first-time donors born before 1970, with the highest rate of HCV. However, the decline has slowed and the profile of HCV-positive first-time donors is changing. A better understanding of behaviour and sources of HCV in younger and ethnic minority donors are needed.

Comparative Analysis of the Radiology of Osteoporotic Vertebral Fractures in Women and Men: Cross-Sectional and Longitudinal Observations from the Canadian Multicentre Osteoporosis Study (CaMos).

We compared two methods for osteoporotic vertebral fracture (VF) assessment on lateral spine radiographs, the Genant semiquantitative (GSQ) technique and a modified algorithm-based qualitative (mABQ) approach. We evaluated 4465 women and 1771 men aged ≥50 years from the Canadian Multicentre Osteoporosis Study with available X-ray images at baseline. Observer agreement was lowest for grade 1 VFs determined by GSQ. Among physician readers, agreement was greater for VFs diagnosed by mABQ (ranging from 0.62 [95% confidence interval (CI) 0.00-1.00] to 0.88 [0.76-1.00]) than by GSQ (ranging from 0.38 [0.17-0.60] to 0.69 [0.54-0.85]). GSQ VF prevalence (16.4% [95% CI 15.4-17.4]) and incidence (10.2/1000 person-years [9.2; 11.2]) were higher than with the mABQ method (prevalence 6.7% [6.1-7.4] and incidence 6.3/1000 person-years [5.5-7.1]). Women had more prevalent and incident VFs relative to men as defined by mABQ but not as defined by GSQ. Prevalent GSQ VFs were predominantly found in the mid-thoracic spine, whereas prevalent mABQ and incident VFs by both methods co-localized to the junction of the thoracic and lumbar spine. Prevalent mABQ VFs compared with GSQ VFs were more highly associated with reduced adjusted L1 to L4 bone mineral density (BMD) (-0.065 g/cm2 [-0.087 to -0.042]), femoral neck BMD (-0.051 g/cm2 [-0.065 to -0.036]), and total hip BMD (-0.059 g/cm2 [-0.076 to -0.041]). Prevalent mABQ VFs compared with prevalent GSQ were also more highly associated with incident VF by GSQ (odds ratio [OR] = 3.3 [2.2-5.0]), incident VF by mABQ (9.0 [5.3-15.3]), and incident non-vertebral major osteoporotic fractures (1.9 [1.2-3.0]). Grade 1 mABQ VFs, but not grade 1 GSQ VFs, were associated with incident non-vertebral major osteoporotic fractures (OR = 3.0 [1.4-6.5]). We conclude that defining VF by mABQ is preferred to the use of GSQ for clinical assessments. © 2017 American Society for Bone and Mineral Research.

Latent variable mixture models to test for differential item functioning: a population-based analysis.

BACKGROUND: Comparisons of population health status using self-report measures such as the SF-36 rest on the assumption that the measured items have a common interpretation across sub-groups. However, self-report measures may be sensitive to differential item functioning (DIF), which occurs when sub-groups with the same underlying health status have a different probability of item response. This study tested for DIF on the SF-36 physical functioning (PF) and mental health (MH) sub-scales in population-based data using latent variable mixture models (LVMMs). METHODS: Data were from the Canadian Multicentre Osteoporosis Study (CaMos), a prospective national cohort study. LVMMs were applied to the ten PF and five MH SF-36 items. A standard two-parameter graded response model with one latent class was compared to multi-class LVMMs. Multivariable logistic regression models with pseudo-class random draws characterized the latent classes on demographic and health variables. RESULTS: The CaMos cohort consisted of 9423 respondents. A three-class LVMM fit the PF sub-scale, with class proportions of 0.59, 0.24, and 0.17. For the MH sub-scale, a two-class model fit the data, with class proportions of 0.69 and 0.31. For PF items, the probabilities of reporting greater limitations were consistently higher in classes 2 and 3 than class 1. For MH items, respondents in class 2 reported more health problems than in class 1. Differences in item thresholds and factor loadings between one-class and multi-class models were observed for both sub-scales. Demographic and health variables were associated with class membership. CONCLUSIONS: This study revealed DIF in population-based SF-36 data; the results suggest that PF and MH sub-scale scores may not be comparable across sub-groups defined by demographic and health status variables, although effects were frequently small to moderate in size. Evaluation of DIF should be a routine step when analysing population-based self-report data to ensure valid comparisons amongst sub-groups.