Occupational Class Inequalities in Physical Health and Work Disability : Causes and Consequences

Socioeconomic position has been consistently found to be connected to health, with those in lower socioeconomic positions having worse health. Inequalities are observed in mortality, individual illnesses, self-rated health, and functioning. While socioeconomic inequalities have been studied extensively over the last decades, there are still gaps in our knowledge. Previous studies have indicated a widening of socioeconomic differences in physical health in late middle-age, but our understanding on the causes of this widening is lacking. Some ageing employees are confronted with work disability and disability retirement, while most eventually transition to mandatory retirement. We also lack knowledge on how different retirement pathways affect the trajectories of physical health in different socioconomic positions. Work ability may also be affected differently in socioeconomic positions after occurrence of serious ill-health. Studies comparing a wide range of causes of inequalities in work disability are scarce. Studying all these different aspects of health and work disability across socioeconomic positions provides a fuller understanding of health and ill-health in different socioeconomic positions, and may provide justification and targets for interventions aiming to reduce the inequalities. The aim of this study was to examine occupational class inequalities in physical health and work disability, assess the major explanations of these inequalities, and examine occupational class inequalities in consequences of ill-health on work disability. The evidence of this study provides material for designing focused interventions to tackle socioeconomic inequalities in physical health and work disability. This study was conducted among the Helsinki Health Study cohort of employees of City of Helsinki, Finland, using both questionnaire survey data and register based data of City of Helsinki employees. The baseline survey data were collected in 2000-2002 (N=8960, response rate 67%), and the follow-up surveys in 2007 (N=7332, response rate 83%) and 2012 (N=6816, response rate 79%). In one sub-study the baseline questionnaire was linked to the retirement register from Finnish Centre for Pensions. In another sub-study the personnel register of all City of Helsinki employees from 1990 to 2013 (N=170510) were linked to national retirement and hospital discharge registers. Information on occupational class was based on job title, and categorized to professionals, semi-professionals, routine non-manual workers and manual workers. Physical health was measured by the physical component summary of the Short Form 36 (SF-36) questionnaire, summarizing different aspects of physical health. The data were analysed using Bayesian hierarchical linear random effects models, mixed effects growth curve models, Cox proportional hazards regression models, and competing risks regression models. Overall the findings of this study indicate the existence of clear occupational class inequalities in physical health among late middle-aged employees, and inequalities are also observed in how health changes over age. The health inequalities also manifest as inequalities in subsequent work disability and as inequalities in consequences of ill-health on work disability. The occupational class differences are likely to be related to differences in accumulation of exposures, particularly physical exposures related to work, and possibly to opportunities to deal with the exposures. .Terveyden on säännöllisesti havaittu olevan alemmissa sosioekonomisissa asemissa huonompaa kuin ylemmissä sosioekonomisissa asemissa. Eriarvoisuutta havaitaan kuolleisuudessa, yksittäisissä sairauksissa, koetussa terveydessä ja toimintakyvyssä. Vaikka sosioekonomisia terveyseroja on viime vuosikymmeninä tutkittu runsaasti, tietämyksessämme on yhä puutteita. Aiemmat tutkimukset viittaavat terveyserojen kasvamiseen myöhäiskeski-ikään asti, mutta ymmärryksemme erojen kasvun syistä on puutteellista. Jotkut ikääntyvät työntekijät kohtaavat työkyvyttömyyttä ja joutuvat työkyvyttömyyseläkkeelle, kun taas suurin osa siirtyy ennen pitkää vanhuuseläkkeelle. Erilaisten eläköitymispolkujen vaikutuksia fyysisen terveyden erojen kehitykseen ei juuri tunneta. Sairastuminen saattaa lisäksi vaikuttaa työkykyyn eri tavoin eri sosioekonomisissa asemissa. Harvat tutkimukset ovat vertailleet laajaa joukkoa eri sosioekonomisissa asemissa olevien henkilöiden työkyvyssä ilmenevän eriarvoisuuden syitä. Kaikkien näiden terveyden ja työkyvyttömyyden eri puolien tutkiminen sosioekonomisissa asemissa mahdollistaa kokonaisvaltaisemman ymmärryksen terveydestä ja sairaudesta sosioekonomisissa asemissa, ja voi myös tarjota perusteluja ja kohteita terveyden eriarvoisuuden vähentämiseen tähtääville interventioille. Tämän tutkimuksen tavoitteena oli tutkia ammattiasemaluokkien välistä eriarvoisuutta fyysisessä terveydessä ja työkyvyttömyydessä, arvioida tämän eriarvoisuuden keskeisimpiä selittäjiä, ja tutkia ammattiasemaluokkien eriarvoisuutta sairauden vaikutuksissa työkyvyttömyyteen. Tämän tutkimuksen näyttö tarjoaa materiaalia kohdennettujen interventioiden suunnitteluun fyysisen terveyden ja työkyvyttömyyden eriarvoisuuden vähentämiseksi. Tutkimus toteutettiin Helsinki Health Study -aineistolla, joka sisältää tietoja Helsingin kaupungin työntekijöiden terveydestä ja siihen vaikuttavista tekijöistä. Tutkimuksessa käytettiin sekä kyselyaineistoja että Helsingin kaupungin työntekijöitä koskevia rekisteriaineistoja. Peruskysely kerättiin vuosina 2000-2002 (N=8960, vastausprosentti 67 %), ja seurantakyselyt vuosina 2007 (N=7332, vastausprosentti 83 %) ja 2012 (N=6816, vastausprosentti 79 %). Kyselyn vastaajien ikä oli peruskyselyssä 40-60 vuotta. Yhdessä osatutkimuksessa peruskysely yhdistettiin Eläketurvakeskuksen eläkerekisteriin. Toisessa osatutkimuksessa koko Helsingin kaupungin työntekijärekisteri vuosilta 1990-2013 (N=170510) yhdistettiin kansalliseen eläkerekisteriin ja hoitoilmoitusrekisteriin. Ammattiasemaluokka määriteltiin ammattinimikkeen perusteella, ja luokiteltiin ylempiin toimihenkilöihin, keskitason toimihenkilöihin, alempiin toimihenkilöihin ja työntekijöihin. Fyysistä terveyttä mitattiin Short Form 36 (SF-36) -kyselypatterin fyysisellä komponenttisummalla, joka kuvaa kokonaisvaltaisesti fyysistä terveyden eri puolia. Aineistoja analysoitiin erilaisilla tilastollisilla malleilla. Kaiken kaikkiaan tämän tutkimuksen tulokset viittaavat siihen, että ammattiasemaluokkien välillä on havaittavissa selkeää eriarvoisuutta fyysisessä toimintakyvyssä, ja eriarvoisuutta havaitaan myös terveyden muuttumisessa iän myötä. Terveyserot ilmenevät myös eriarvoisuutena työkyvyttömyydessä ja sairastumisen seurauksissa työkyvyttömyydelle. Ammattiasemaluokkien väliset erot liittyvät luultavasti eroihin altistusten kertymisessä, erityisesti työhön liittyviin fyysisiin altisteisiin, ja mahdollisesti erilaisiin mahdollisuuksiin reagoida haitallisiin altistuksiin

Rare Genomic Deletions underlying Schizophrenia and Related Neurodevelopmental Disorders

Severe mental disorders including schizophrenia often segregate within the same families. Twin and family studies suggest that this co-occurrence is largely genetic, which implies that the different mental disorders have a shared genetic background. Some symptomatic features, such as cognitive impairment also manifest to a variable degree in the majority of severe mental disorders. Cognitive impairment occurs already before the onset of the disease and healthy family members of patients perform worse in cognitive tests than do the general population, which suggests that the cognitive impairment is indicative of genetic loading of the disease. Furthermore, the cognitive impairment persists throughout the disease and is associated with poorer outcome. This led us to hypothesize that the genetic architecture of schizophrenia is more similar to developmental disorders than had been considered earlier. Specifically, we hypothesized that rare high impact genetic variants play a role in the genetic risk for schizophrenia. Rare recurrent large-scale structural variation has long known to cause developmental syndromes, such as Prader-Willi syndrome or Velocardiofacial syndrome. In this study we investigated the role of large-scale chromosomal copy number variants in the genetic background of schizophrenia and other traits hypothesized to reflect abnormal neuronal development. In this study four chromosomal deletions on 1q21, 15q11.2, 15q13.3 and 22q11.2 were identified to be associated with schizophrenia. Three of the deletions occurred recurrently, whereas the deletion on 22q11.22 was a founder mutation enriched especially in the North-East region of Finland. On a population level, carriers of large deletions were found to have more intellectual disability or sub-normality (IQ<85) than non-carriers. Also milder learning difficulties as measured by repeated grades in school were more common among carriers of large deletions. The four deletions specifically identified as associating with schizophrenia are linked to variable phenotypes with the strongest effect manifesting in intellectual disabilities. The regional enrichment of the deletion on 22q11.22 also enabled the assessment of recessive effects related to the deletion. Four individuals, all presenting with a neurodevelopmental phenotype and/or schizophrenia, were identified as homozygous for the deletion. This deletion overlaps one gene encoding for topoisomerase 3 beta (TOP3β) that forms a protein complex with FMRP, the fragile X mental retardation protein, via tudor domain containing 3 (TDRD3) protein. The results of this study imply that rare high risk variants are present in a sub set of schizophrenia patients and that these variants are shared with developmental disorders. The study also demonstrates that special populations such as population isolates can provide useful study designs in identifying rare genetic risk variants, especially with recessive effects for complex traits.Monet vakavat mielenterveydenhäiriöt, kuten skitsofrenia, kasaantuvat usein samoihin perheisiin. Kaksos- ja perhetutkimusten perusteella tämä yhteisesiintyminen selittyy suurelta osin geneettisillä tekijöillä, mikä viittaisi siihen, että useat diagnostisesti erotellut mielenterveyden häiriöt jakavat osan geneettisestä taustasta keskenään. Tätä tukee myös se, että osa sairauksien oireista, kuten kognitiivisten eli tiedonkäsittelyyn liittyvien toimintojen häiriöt, ovat samankaltaisia joskin vaikeusasteeltaan vaihtelevia useimmissa vakavissa mielenterveyshäiriöissä. Kognitiivisten toimintojen häiriöt ovat erityisen tavallisia skitsofreniaa sairastavilla. Ne ilmaantuvat potilailla jo ennen varsinaisen taudin puhkeamista, ja niitä esiintyy myös terveillä perheenjäsenillä. Kognitiivisten toimintojen häiriöt saattavatkin olla merkki geneettisestä alttiudesta sairauteen. Ne säilyvät läpi sairauden ja ennustavat usein huonompaa hoitotulosta. Tämä oli lähtökohtana oletukselle, että skitsofrenian geneettinen arkkitehtuuri olisi samankaltaisempi kehityksellisten sairauksien, kuten älyllisen kehitysvammaisuuden, kanssa kuin mitä aiemmin on oletettu. Tässä tutkimuksessa oletettiin erityisesti, että harvinaiset geneettiset muutokset, joihin liittyy suuri sairastumisriski, olisivat tärkeitä skitsofrenian geneettisessä etiologiassa. Harvinaisten suurikokoisten perimän rakenteellisten muutosten on pitkään tiedetty aiheuttavan normaalin kehityksen häiriöitä ja oireyhtymiä, kuten Prader-Willin tai velokardiofasiaalisen oireyhtymän. Tässä tutkimuksessa selvitettiin isokokoisten perimän kopiolukumuutosten osuutta skitsofrenian geneettisessä taustassa ja ominaisuuskissa, joiden oletimme heijastelevan hermoston kehityksen häiriötä. Tutkimuksessa tunnistettiin neljä perimän poistumaa eli deleetiota kromosomeissa 1q21, 15q11.2, 15q13.3 ja 22q11.22, jotka assosioituivat skitsofreniaan. Kolme deleetioista ilmaantuvat toistuvasti, kun taas 22q11.22-deleetio on perustajamutaatio, joka on rikastunut väestöön erityisesti Suomessa Koillismaalla. Väestötasolla isojen deleetioiden kantajissa yleisesti havaittiin enemmän älyllisen kehityksen häiriöitä (älykkyysosamäärä alle 85) kuin henkilöissä, joilla ei havaittu isokokoisia deleetioita. Myös lievemmät oppimisvaikeudet, määriteltynä henkilön luokalle jääntinä olivat yliedustettuina suurien deleetioiden kantajissa. Kaikki neljä tunnistettua deleetiota assosioituvat vaihtelevaan ilmiasuun, jossa suurin vaikutus näyttäisi olevan juuri älyllisiin kykyihin. 22q11.22- deleetion alueellinen rikastuminen mahdollisti siihen liittyvien peittyvien ominaisuuksien tutkimisen. Neljä henkilöä kantoi kromosomin 22q11.22 deleetioita homotsygoottisesti. Heillä kaikilla on diagnosoitu skitsofrenia tai älyllisen kehityksen häiriö. Deleetio poistaa topoisomeraasi 3 beeta proteiinia koodittavan geenin (TOP3β). TOP3β proteiinin havaittiin muodostavan proteiinikompleksin FMRP:n (fragile X mental retardation protein) kanssa TDRD3 (Tudor domain containing 3) proteiinin välityksellä. Tutkimuksen tulokset osoittavat, että pieni osajoukko skitsofreniaa sairastavista kantaa harvinaisia suuren sairastumisriskin geneettisiä muutoksia. Nämä muutokset on lisäksi jaettuja kehityksellisten häiriöiden kanssa. Tutkimus osoittaa, että geneettisesti eristäytyneet väestöt voivat tarjota edullisia tutkimusasetelmia erityisesti harvinaisten haitallisten geneettisten muutosten tunnistamisessa monitekijäisten sairauksien taustalla. Varsinkin muutoksiin liittyvien peittyvien vaikutusten havaitseminen voi olla helpompaa näissä väestöissä

Kartasta tuli uutinen: liikkuvien karttojen nousu datajournalismissa ja verkon uudet karttatoteutukset

Digitalisoituvista liikkuvista kartoista tiedetään vielä vähän yhteydessä tiedon visualisointiin uutisissa. Tutkielmassa havainnoidaan vallitsevia karttaesitysmuotoja ja toteutetaan kolme eri karttatyyppiä, eli esimerkkitoteutusta, liikkuvista kartoista. Liike kartoissa on synnyttänyt uusia tapoja kertoa asioita lukijoille. Sitä, miten liikkuvien karttoja tehdään, harvoin pystytään problematisoimaan nopeassa toimitustyössä. Vaihtoehtoisia graafisen esittämisen keinoja on kuitenkin esitetty informaation visualisointiin kartoilla. Tekijän ongelma on välineiden häviäminen ja muutos tuotantotavoissa. Kartografian uudet palvelut muokkaavat teknisiä odotuksia esimerkiksi sinisen pisteen (Googlen My Location) osalta. Työssä ohjelmoijalla on oltava paljon tietoa työkaluista ja alustoista mukaan lukien tietämys prosessuaalisista kartoista. Verkko kiihdyttää muutosta, jossa tekijöiden roolit hajautuvat, ja lukijat ovat osa jutun työstämistä

Trajectories of working hours in later careers and their association with social and health-related factors : a follow-up study

Background The aim was to identify working hours’ trajectories in later work careers over a follow-up of 15–17 years and to examine their association with social factors and health. Methods A subsample from the Helsinki Health Study was extracted comprising employees of the City of Helsinki, Finland. Growth mixture modelling was used to identify different working hour trajectories. Age, gender, occupational class, marital status, health behaviour, physical and mental functioning and current pain were associated with trajectory membership. Relative risks (RRs) and their 95% confidence intervals (CIs) were estimated. Results A two-trajectory model was selected: ‘Stable regular working hours’ (90%) and ‘Shorter and varying working hours’ (10%). Women (RR 1.40, 95% CI 1.09–1.78), the oldest employees (RR 2.71, 95% CI 2.06–3.57), managers and professionals (RR 1.56, 95% CI 1.20–2.02), those reporting non-drinker (RR 1.66, 95% CI 1.32–2.10), those reporting sleeping more than 8 h per night (RR 1.74 95% CI 1.25–2.42) and those reporting poor mental functioning (RR 1.39 95% CI 1.15–1.68) had higher likelihood of belonging to the trajectory ‘Shorter and varying working hours’. There were no differences between the trajectories in marital status, smoking, body mass index, current pain or physical functioning. However, routine non-manual workers (RR 0.74, 95% CI 0.55–0.98), and semi-professionals (RR 0.70, 95% CI 0.50–0.96) had lower likelihood of belonging to this trajectory. Conclusions Trajectories of working hours in later work career differ by age, gender and occupational class but also by health behaviours and mental health functioning.Peer reviewe

Contributions of childhood adversities to chronic pain among midlife employees

Aims: Chronic pain is a notable burden on public health, with past and present factors contributing to it. This study aimed to examine the associations between childhood adversities and chronic pain. Methods: Data on seven childhood adversities, chronic pain and disabling pain were derived from questionnaire surveys conducted in 2000, 2001 and 2002 among 40- to 60-year-old employees (response rate of 67%) of the City of Helsinki, Finland. The study included 8140 employees (80% women). Logistic regression was used in the analyses, and the results are presented as odds ratios (OR) and their 95% confidence intervals (CI). Age, sex, the father's education, the participant's education, marital status, working conditions, sleep problems and common mental disorders were included as covariates. Results: In the age-adjusted models, childhood economic difficulties (OR=1.60, 95% CI 1.41-1.81), childhood illness (OR=1.74, 95% CI 1.45-2.08), parental divorce (OR=1.26, 95% CI 1.07-1.48), parental alcohol problems (OR=1.34, 95% CI 1.18-1.52) and bullying at school or among peers (OR=1.59, 95% CI 1.37-1.89) were associated with chronic pain. Working conditions, sleep problems and common mental disorders each slightly attenuated the associations between childhood adversities and chronic pain. Childhood economic difficulties among women (OR=1.72, 95% CI 1.40-2.10), childhood illness (OR=1.40, 95% CI 1.07-1.82) and bullying at school or by peers (OR=1.91 95% CI 1.48-2.46) were also associated with disabling pain. Conclusions: Childhood adversities were associated with chronic pain in mid-life, and the associations mainly remained after adjustments. Investing in the well-being of children might prevent pain and promote well-being in mid-life.Peer reviewe

Multiple Socioeconomic Circumstances and Initiation of Cardiovascular Medication among Ageing Employees

There are persisting socioeconomic differences in cardiovascular diseases, but studies on socioeconomic differences in the initiation of cardiovascular medication are scarce. This study examined the associations between multiple socioeconomic circumstances and cardiovascular medication. The Helsinki Health Study baseline survey (2000-2002) of 40-60-year-old employees was linked with cardiovascular medication data from national registers. The analyses included 5805 employees concerning lipid medication and 4872 employees concerning hypertension medication. Medication purchases were followed for 10 years. The analyses were made using logistic regression, and the odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated for childhood, conventional and material socioeconomic circumstances. Low parental education showed an association with lipid medication among women only (OR 1.34, 95% CI 1.11-1.61), whereas childhood economic difficulties showed more widespread associations. Low education and occupational class were associated with an increased risk of both hypertension (education: OR 1.58, 1.32-1.89; occupational class: 1.31, 1.08-1.59) and lipid medication (education: 1.34, 1.12-1.61; occupational class: 1.38, 1.13-1.67). Rented housing (1.35, 1.18-1.54 for hypertension medication; 1.21, 1.05-1.38 for lipid medication) and current economic difficulties (1.59, 1.28-1.98 for hypertension medication; 1.35, 1.07-1.71 for lipid medication) increased the risk. Several measures of socioeconomic circumstances acting at different stages of the life course were associated with cardiovascular medication, with individuals in disadvantageous socioeconomic circumstances having elevated risks.Peer reviewe

Trajectories of multisite musculoskeletal pain in midlife : Associations with common mental disorders

Objectives We examined developmental trajectories of multisite musculoskeletal pain in midlife, and their associations with mental well-being. Methods Midlife municipal employees at baseline aged 40, 45, 50, 55 or 60 years (80% women) from the City of Helsinki, Finland, responded to a baseline questionnaire in 2000-02 (N = 8,960; response rate 67%) and follow-ups in 2007 (N = 7,332; 83%) and 2012 (N = 6,809; 78%). Trajectories of the number of pain sites (0-4) were modelled using latent class growth analysis (n = 6,527). Common mental disorders were assessed by the General Health Questionnaire (GHQ) 12-item version (trichotomized to low, intermediate or high). Information on health-related behaviour, comorbidity and socioeconomic position was obtained from the questionnaire. Associations of baseline factors with pain trajectories were assessed by multinomial logistic regression. Results We identified four distinct pain trajectories: high (15%), increasing (24%), decreasing (20%) and low (41%). After an initial increase, the high and increasing trajectories stabilized at around 2.5 and 1.5 pain sites respectively. In a multivariable model, high, increasing and decreasing trajectories of pain sites were associated with higher baseline GHQ scores. The association was strongest for the high trajectory (low GHQ: OR 3.7, 95% CI 2.8-4.9; high GHQ: OR 5.4, 95% 4.4-6.6). Trajectory membership also associated with unhealthy behaviours, musculoskeletal comorbidities and a low socioeconomic position at baseline. Average GHQ was consistently highest for the high pain trajectory and decreased in the decreasing trajectory over the follow-up. Conclusions Multisite musculoskeletal pain shows variable developmental patterns among midlife employees. The trajectories are associated with the level of common mental disorders. Significance Four developmental trajectories of multisite pain in midlife were described over 10-12 years of follow-up: low (41% of the sample), increasing (24%), high (15%) and decreasing (20%). Common mental disorders strongly associated with these. Belonging to the highest tertile of mental disorders at baseline increased the risk of membership in the high trajectory more than fivefold. On the other hand, together with a decrease in mental disorders, the number of pain sites decreased to zero.Peer reviewe

Intergenerational social mobility and body mass index trajectories – A follow-up study from Finland

Evidence remains unclear on how intergenerational social mobility is associated with body mass index (BMI) and its long-term changes. Our study identified BMI trajectories from middle to older age by intergenerational social mobility groups and stratified the analyses by gender and two birth cohorts (birth years 1940‒1947 and 1950–1962). We used questionnaire-based cohort data that consists of four survey phases: 2000–2002, 2007, 2012, and 2017. In Phase 1, participants were 40–60-year-old employees of the City of Helsinki, Finland. Our analytical sample consisted of 6,971 women and 1,752 men. Intergenerational social mobility was constructed based on self-reported parental and own education—both divided into high and low—yielding four groups: stable high socioeconomic position (SEP) (high-high), upward social mobility (low-high), downward social mobility (high-low), and stable low SEP (low-low). BMI was calculated from self-reported height and weight from all four phases. Using mixed-effects linear regression, we found increasing BMI trajectories in all four social mobility groups until the age of 65. Women and men with stable high SEP had lower BMI trajectories compared to those with stable low SEP. In the younger birth cohort, women with upward social mobility had a lower BMI trajectory than women with stable low SEP. Additionally, women and men with downward social mobility had higher BMI trajectories than those with stable high SEP. In the older birth cohort, however, the BMI trajectories of upward and downward social mobility groups were somewhat similar and settled between the BMI trajectories of stable high and stable low SEP groups. Our results indicate that the associations between intergenerational social mobility and BMI may depend on gender and birth cohort. Nevertheless, to reduce socioeconomic inequalities in unhealthy weight gain, obesity prevention actions that focus on people who are likely to remain in low SEP might be worthwhile.Peer reviewe

Factors associated with health survey response among young employees : a register-based study using online, mailed and telephone interview data collection methods

Background: Declining response rates are a common challenge to epidemiological research. Response rates further are particularly low among young people. We thus aimed to identify factors associated with health survey response among young employees using different data collection methods. Methods: We included fully register-based data to identify key socioeconomic, workplace and health-related factors associated with response to a health survey collected via online and mailed questionnaires. Additionally, telephone interviews were conducted for those who had not responded via online or to the mailed survey. The survey data collection was done in autumn 2017 among young employees of the City of Helsinki, Finland (18-39 years, target population n=11,459). Results: The overall response to the survey was 51.5% (n=5898). The overall findings suggest that differences in the distributions of socioeconomic, workplace and health-related factors between respondents in the online or mailed surveys, or telephone interviews, are relatively minor. Telephone interview respondents were of lower socioeconomic position, which helped improve representativeness of the entire cohort. Despite the general broad representativeness of the data, some socioeconomic and health-related factors contributed to response. Thus, non-respondents were more often men, manual workers, from the lowest income quartile, had part-time jobs, and had more long sickness absence spells. In turn, job contract (permanent or temporary) and employment sector did not affect survey response. Conclusions: Despite a general representativeness of data of the target population, socioeconomically more disadvantaged and those with long sickness absence, are slightly overrepresented among non-respondents. This suggests that when studying the associations between social factors and health, the associations can be weaker than if complete data were available representing all socioeconomic groups.Peer reviewe