Measuring socioeconomic position in health research

OBJECTIVE

In this article we review different measures of socioeconomic position (SEP) and their uses in health-related research.

AREAS OF AGREEMENT

Socioeconomic circumstances influence health.

AREAS OF CONTROVERSY

Generally, poorer socioeconomic circumstances lead to poorer health. This has generated a search for generic mechanisms that could explain such a general association. However, we propose that there is a greater variation in the association between SEP and health than is generally acknowledged when specific health outcomes are investigated. We propose that studying these variations provide a better understanding of the aetiological mechanisms relating specific diseases with specific exposures. AREAS TO DEVELOP RESEARCH: Using different indicators of SEP in health research can better capture these variations and is important when evaluating the full contribution of confounding by socioeconomic conditions. We propose that using an array of SEP indicators within a life course framework also offers considerable opportunity to explore causal pathways in disease aetiology.

Quantitative measures of air-gun pulses recorded on sperm whales (Physeter macrocephalus) using acoustic tags during controlled exposure experiments

The widespread use of powerful, low-frequency air-gun pulses for seismic seabed exploration has raised concern about their potential negative effects on marine wildlife. Here, we quantify the sound exposure levels recorded on acoustic tags attached to eight sperm whales at ranges between 1.4 and 12.6 km from controlled air-gun array sources operated in the Gulf of Mexico. Due to multipath propagation, the animals were exposed to multiple sound pulses during each firing of the array with received levels of analyzed pulses falling between 131-167 dB re. 1 microPa (pp) [111-147 dB re. 1 microPa (rms) and 100-135 dB re. 1 microPa2 s] after compensation for hearing sensitivity using the M-weighting. Received levels varied widely with range and depth of the exposed animal precluding reliable estimation of exposure zones based on simple geometric spreading laws. When whales were close to the surface, the first arrivals of air-gun pulses contained most energy between 0.3 and 3 kHz, a frequency range well beyond the normal frequencies of interest in seismic exploration. Therefore air-gun arrays can generate significant sound energy at frequencies many octaves higher than the frequencies of interest for seismic exploration, which increases concern of the potential impact on odontocetes with poor low frequency hearing.

Promoting absorption of drugs in humans using medium-chain fatty acid-based solid dosage forms: GIPET™

One of the most important and challenging goals in drug delivery is overcoming the poor oral absorption of high-value therapeutics that include peptides. Gastrointestinal Permeation Enhancement Technology (GIPET) attempts to address this question by safely delivering drugs across the small intestine in therapeutically relevant concentrations. GIPET is based primarily on promoting drug absorption through the use of medium-chain fatty acids, medium-chain fatty acid derivatives and microemulsion systems based on medium-chain fatty acid glycerides formulated in enteric-coated tablets or capsules. Importantly, these excipients are generally regarded as safe and the systems are formulated in such a way that there is no change in chemical composition of the active ingredient. More than 300 volunteers have been administered GIPET formulations in 16 Phase I studies of 6 separate drugs comprising both single- and repeat-dosing regimes. Oral bioavailability of alendronate, desmopressin and low-molecular-weight heparin in humans was increased using GIPET formulations compared with unformulated controls. GIPET was well tolerated by human subjects. Using fluxes of markers of epithelial permeability, the effects of GIPET on the human intestine were shown to be rapid, short-lived and reversible in vivo. These data suggest that GIPET formulations have genuine potential as a platform technology for safe and effective oral drug delivery of a wide range of poorly permeable drugs.

Effects of socioeconomic change from birth to early adulthood on height and overweight

BACKGROUND

In this work we explored the association of height and overweight with change in socioeconomic position between birth and 19 years of age.

METHODS

A birth cohort has been followed-up in Pelotas, Brazil, since 1982. All 5914 hospital births were enrolled in the study just after delivery. In 2001, 27% of the cohort subjects were sought, and 1031 (69% of the survivors) were interviewed. Weight and height were obtained for women; men had been examined 6 months earlier. Information on family income in 1982 and 2001 was used to classify the sample into tertiles, the lowest classified as 'poor' and the other two as 'non-poor'. Four trajectories resulted: always poor, never poor, poor at birth/non-poor at 19, and non-poor at birth/poor at 19-which were compared in terms of mean height and prevalence of overweight.

RESULTS

Height showed a similar behaviour for men and women, with the never poor presenting the highest mean, followed by those who were non-poor at birth and later became poor. Those who were poor at birth, regardless of later status, were shortest. Overweight was approximately twice as common among men who were never poor in relation to the others. Among women, those who were always poor presented the highest prevalence of overweight. In this case, social determination seems to be complex and may involve aspects of lifestyle and behaviour acting differently for each gender.

CONCLUSION

Socioeconomic trajectories affected both height and overweight, the effect on the latter being different for each gender.

The relation between socioeconomic and demographic factors and tumour stage in women diagnosed with breast cancer in Denmark, 1983-1999

The authors investigated the association between socioeconomic position and stage of breast cancer at the time of diagnosis in a nationwide Danish study. All 28 765 women with a primary invasive breast cancer diagnosed between 1983 and 1999 were identified in a nationwide clinical database and information on socioeconomic variables was obtained from Statistics Denmark. The risk of being diagnosed with a high-risk breast cancer, that is size >20 mm, lymph-node positive, ductal histology/high histologic grade and hormone receptor negative, was analysed by multivariate logistic regression. The adjusted odds ratio (OR) for high-risk breast cancer was reduced with longer education with a 12% reduced risk (95% confidence interval (CI), 0.80,0.96) in women with higher education and increased with reduced disposable income (low income group: OR, 1.22; 95% CI, 1.10,1.34). There was an urban–rural gradient, with higher risk among rural women (OR 1.10; 95 % CI, 1.02, 1.18) and lower risk among women in the capital suburbs (OR, 0.85; 95% CI, 0.78, 0.93) and capital area (OR, 0.93; 95% CI, 0.84–1.02). These factors were significant only for postmenopausal women, although similar patterns were observed among the premenopausal women, suggesting a subgroup of aggressive premenopausal breast cancers less influenced by socioeconomic factors.

Similar support for three different life course socioeconomic models on predicting premature cardiovascular mortality and all-cause mortality

Background

There are at least three broad conceptual models for the impact of the social environment on adult disease: the critical period, social mobility, and cumulative life course models. Several studies have shown an association between each of these models and mortality. However, few studies have investigated the importance of the different models within the same setting and none has been performed in samples of the whole population. The purpose of the present study was to study the relation between socioeconomic position (SEP) and mortality using different conceptual models in the whole population of Scania.

Methods

In the present investigation we use socioeconomic information on all men (N = 48,909) and women (N = 47,688) born between 1945 and 1950, alive on January, 1^st,1990, and living in the Region of Scania, in Sweden. Focusing on three specific life periods (i.e., ages 10–15, 30–35 and 40–45), we examined the association between SEP and the 12-year risk of premature cardiovascular mortality and all-cause mortality.

Results

There was a strong relation between SEP and mortality among those inside the workforce, irrespective of the conceptual model used. There was a clear upward trend in the mortality hazard rate ratios (HRR) with accumulated exposure to manual SEP in both men (p for trend < 0.001 for both cardiovascular and all-cause mortality) and women (p for trend = 0.01 for cardiovascular mortality) and (p for trend = 0.003 for all-cause mortality). Inter- and intragenerational downward social mobility was associated with an increased mortality risk. When applying similar conceptual models based on workforce participation, it was shown that mortality was affected by the accumulated exposure to being outside the workforce.

Conclusion

There was a strong relation between SEP and cardiovascular and all-cause mortality, irrespective of the conceptual model used. The critical period, social mobility, and cumulative life course models, showed the same fit to the data. That is, one model could not be pointed out as "the best" model and even in this large unselected sample it was not possible to adjudicate which theories best describe the links between life course SEP and mortality risk.

Family information service (FIS) in a BRCA1 extended family

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Background: Considering that 10% of breast cancer is hereditary, it is essential to effectively educate hereditary cancer family members regarding the syndrome, cancer risk, genetic testing and cancer control options. Researchers at Creighton University (CU) have for many years provided family (group-oriented) information services (FISs) for hereditary cancer families. Methods: Such a session was held in collaboration with a genetic counselor in a community where many members of an extended hereditary breast-ovarian cancer family with a known BRCA1 mutation reside. Family members helped contact relatives and invited them to attend the full-day FIS at a local hospital. Informal presentations were provided by a CU geneticist/oncologist, a CU nurse counselor, and a local genetic counselor. Questions and comments were encouraged. An opportunity to provide a blood sample for genetic testing was offered. Results: Contacting relatives for the FIS identified more than 400 family members from previously unknown branches. Many attendees indicated this was their first opportunity to learn about this hereditary cancer syndrome, their risk, and recommended cancer control options. Patient-stated benefits of the FIS included increased communication of cancer risk among family members as well as with their physicians, motivation to become more vigilant with screening and health management and receipt of initial cancer risk education in a non-threatening venue. Conclusions: The FIS is a relatively simple, cost-effective educational cancer control program that increases communication among family members and their physicians, educates high-risk individuals and provides an opportunity for genetic testing which will ultimately provide an accurate cancer risk status and thereby alter health management and cancer control strategies.

No significant financial relationships to disclose.

A brief conceptual tutorial on multilevel analysis in social epidemiology: interpreting neighbourhood differences and the effect of neighbourhood characteristics on individual health

STUDY OBJECTIVE

Using a conceptual rather than a mathematical approach, this article proposed a link between multilevel regression analysis (MLRA) and social epidemiological concepts. It has been previously explained that the concept of clustering of individual health status within neighbourhoods is useful for operationalising contextual phenomena in social epidemiology. It has been shown that MLRA permits investigating neighbourhood disparities in health without considering any particular neighbourhood characteristic but only information on the neighbourhood to which each person belongs. This article illustrates how to analyse cross level (neighbourhood-individual) interactions, how to investigate associations between neighbourhood characteristics and individual health, and how to use the concept of clustering when interpreting those associations and geographical differences in health.

DESIGN AND PARTICIPANTS

A MLRA was performed using hypothetical data pertaining to systolic blood pressure (SBP) from 25 000 subjects living in the 39 neighbourhoods of an imaginary city. Associations between individual characteristics (age, body mass index (BMI), use of antihypertensive drug, income) or neighbourhood characteristic (neighbourhood income) and SBP were analysed.

RESULTS

About 8% of the individual differences in SBP were located at the neighbourhood level. SBP disparities and clustering of individual SBP within neighbourhoods increased along individual BMI. Neighbourhood low income was associated with increased SBP over and above the effect of individual characteristics, and explained 22% of the neighbourhood differences in SBP among people of normal BMI. This neighbourhood income effect was more intense in overweight people.

CONCLUSIONS

Measures of variance are relevant to understanding geographical and individual disparities in health, and complement the information conveyed by measures of association between neighbourhood characteristics and health.

Genes and race in the news: a test of competing theories of news coverage

OBJECTIVES

To examine newspaper coverage of race and genetics to identify patterns and possible explanations for them in extant theory in order to improve health promotion campaigns.

METHODS

Articles from Lexus-Nexus database fitting the search criteria were coded according to themes developed from the scientific literature and a prereading of texts.

RESULTS

Articles present an array of attitudes toward race and genetics. No existing theory explains this pattern.

CONCLUSION

Because newspapers present both sides of the scientific debate, health promotion messages dealing with race, genetics, and medicine must address both sides of the debate in order to be effective.

Explaining the social gradient in coronary heart disease: comparing relative and absolute risk approaches

STUDY OBJECTIVES

There are contradictory perspectives on the importance of conventional coronary heart disease (CHD) risk factors in explaining population levels and social gradients in CHD. This study examined the contribution of conventional CHD risk factors (smoking, hypertension, dyslipidaemia, and diabetes) to explaining population levels and to absolute and relative social inequalities in CHD. This was investigated in an entire population and by creating a low risk sub-population with no smoking, dyslipidaemia, diabetes, and hypertension to simulate what would happen to relative and social inequalities in CHD if conventional risk factors were removed.

DESIGN, SETTING, AND PARTICIPANTS

Population based study of 2682 eastern Finnish men aged 42, 48, 54, 60 at baseline with 10.5 years average follow up of fatal (ICD9 codes 410-414) and non-fatal (MONICA criteria) CHD events.

MAIN RESULTS

In the whole population, 94.6% of events occurred among men exposed to at least one conventional risk factor, with a PAR of 68%. Adjustment for conventional risk factors reduced relative social inequality by 24%. However, in a low risk population free from conventional risk factors, absolute social inequality reduced by 72%.

CONCLUSIONS

Conventional risk factors explain the majority of absolute social inequality in CHD because conventional risk factors explain the vast majority of CHD cases in the population. However, the role of conventional risk factors in explaining relative social inequality was modest. This apparent paradox may arise in populations where inequalities in conventional risk factors between social groups are low, relative to the high levels of conventional risk factors within every social group. If the concern is to reduce the overall population health burden of CHD and the disproportionate population health burden associated with the social inequalities in CHD, then reducing conventional risk factors will do the job.

Contribution of main causes of death to social inequalities in mortality in the whole population of Scania, Sweden

BACKGROUND

To more efficiently reduce social inequalities in mortality, it is important to establish which causes of death contribute the most to socioeconomic mortality differentials. Few studies have investigated which diseases contribute to existing socioeconomic mortality differences in specific age groups and none were in samples of the whole population, where selection bias is minimized. The aim of the present study was to determine which causes of death contribute the most to social inequalities in mortality in each age group in the whole population of Scania, Sweden.

METHODS

Data from LOMAS (Longitudinal Multilevel Analysis in Skåne) were used to estimate 12-year follow-up mortality rates across levels of socioeconomic position (SEP) and workforce participation in 975,938 men and women aged 0 to 80 years, during 1991-2002.

RESULTS

The results generally showed increasing absolute mortality differences between those holding manual and non-manual occupations with increasing age, while there were inverted u-shaped associations when using relative inequality measures. Cardiovascular diseases (CVD) contributed to 52% of the male socioeconomic difference in overall mortality, cancer to 18%, external causes to 4% and psychiatric disorders to 3%. The corresponding contributions in women were 55%, 21%, 2% and 3%. Additionally, those outside the workforce (i.e., students, housewives, disability pensioners, and the unemployed) showed a strongly increased risk of future mortality in all age groups compared to those inside the workforce. Even though coronary heart disease (CHD) played a major contributing role to the mortality differences seen, stroke and other types of cardiovascular diseases also made substantial contributions. Furthermore, while the most common types of cancers made substantial contributions to the socioeconomic mortality differences, in some age groups more than half of the differences in cancer mortality could be attributed to rarer cancers.

CONCLUSION

CHD made a major contribution to the socioeconomic differences in overall mortality. However, there were also important contributions from diseases with less well understood mechanistic links with SEP such as stroke and less-common cancers. Thus, an increased understanding of the mechanisms connecting SEP with more rare causes of disease might be important to be able to more successfully intervene on socioeconomic differences in health.

A brief conceptual tutorial on multilevel analysis in social epidemiology: investigating contextual phenomena in different groups of people

STUDY OBJECTIVE

(1) To provide a didactic and conceptual (rather than mathematical) link between multilevel regression analysis (MLRA) and social epidemiological concepts. (2) To develop an epidemiological vision of MLRA focused on measures of health variation and clustering of individual health status within areas, which is useful to operationalise the notion of "contextual phenomenon". The paper shows how to investigate (1) whether there is clustering within neighbourhoods, (2) to which extent neighbourhood level differences are explained by the individual composition of the neighbourhoods, (3) whether the contextual phenomenon differs in magnitude for different groups of people, and whether neighbourhood context modifies individual level associations, and (4) whether variations in health status are dependent on individual level characteristics.

DESIGN AND PARTICIPANTS

Simulated data are used on systolic blood pressure (SBP), age, body mass index (BMI), and antihypertensive medication (AHM) ascribed to 25 000 subjects in 39 neighbourhoods of an imaginary city. Rather than assessing neighbourhood variables, the paper concentrated on SBP variance between individuals and neighbourhoods as a function of individual BMI.

RESULTS

The variance partition coefficient (VPC) showed that clustering of SBP within neighbourhoods was greater for people with a higher BMI. The composition of the neighbourhoods with respect to age, AHM use, and BMI explained about one fourth of the neighbourhood differences in SBP. Neighbourhood context modified the individual level association between BMI and SBP. Individual level differences in SBP within neighbourhoods were larger for people with a higher BMI.

CONCLUSIONS

Statistical measures of multilevel variations can effectively quantify contextual effects in different groups of people, which is a relevant issue for understanding health inequalities.

Disentangling contextual effects on cause-specific mortality in a longitudinal 23-year follow-up study: impact of population density or socioeconomic environment?

BACKGROUND

Various studies have investigated urban/rural differences in cause-specific mortality. A separate body of literature has analysed effects of socioeconomic environment on mortality. Almost no studies have attempted to disentangle effects of population density and socioeconomic environment on mortality, beyond the effects of individual characteristics.

METHODS

Considering all individuals living in the region of Scania, Sweden, from 1970-93, we performed 10 year mortality follow-ups on (i) individuals aged 55, (ii) individuals aged 65, and (iii) individuals aged 75 years at baseline. Cox multilevel models adjusted for individual factors allowed us to investigate the independent effects of population density and median income in the parish of residence on mortality from ischaemic heart disease (IHD), lung cancer, and chronic obstructive pulmonary disease (COPD) among individuals who had lived in the same parish for at least 10 years prior to mortality follow-up.

RESULTS

In females, as in males, after adjustment for individual and contextual socioeconomic status, we found a dose-response association between population density and mortality from lung cancer and COPD in all age groups investigated, and from IHD especially in the youngest age group. Overall, the population density effect was the strongest on lung cancer mortality. Median income had an additional impact only in 2 out of 16 subgroups of age x gender x cause of death.

CONCLUSIONS

In our region-wide study conducted at the parish level, contextual disparities in mortality were dominated by the population density effect. However, it may be unwise to conclude that truly contextual effects exist on mortality, before identification of plausible mediating processes through which urbanicity may influence mortality risk.

Drugs and double binds: racial identification and pharmacogenomics in a system of binary race logic

People respond to drugs in different ways depending on their genotype. Some geneticists and medical researchers have suggested using race as a substitute for genotype in prescribing medication. Overall, individuals resist the prescription of medication based on race, but some minority individuals, although indicating resistance and suspicion, ultimately choose race-based medication. This can be explained by the operation of Burkean identification in a system of binary race logic. Although individuals resist race-based medication and recognize race is not a legitimate genetic category, their identification with a racial-ethnic group places them in a double bind between choosing race-based medication or denying their racial identification.

Spatially-oriented EMR for dental surgery

As digital dental images become widely available, a new Electronic MR system (EMR) will be critical for the success of applying new technology to dental care. This project is designed an image-based and spatially-oriented EMR for dental surgery. A new panoramic image-based annotation model will be developed, which will complement dental charting precisely locating specific spatial findings for each patient. A spatially-oriented, multilayered data model for dental EMR will be developed using Geographic Information System (GIS) methods. This project will explore the possibility of applying head and neck images from VHP into a spatially-oriented EMR system.

A brief conceptual tutorial of multilevel analysis in social epidemiology: linking the statistical concept of clustering to the idea of contextual phenomenon

STUDY OBJECTIVE

This didactical essay is directed to readers disposed to approach multilevel regression analysis (MLRA) in a more conceptual than mathematical way. However, it specifically develops an epidemiological vision on multilevel analysis with particular emphasis on measures of health variation (for example, intraclass correlation). Such measures have been underused in the literature as compared with more traditional measures of association (for example, regression coefficients) in the investigation of contextual determinants of health. A link is provided, which will be comprehensible to epidemiologists, between MLRA and social epidemiological concepts, particularly between the statistical idea of clustering and the concept of contextual phenomenon.

DESIGN AND PARTICIPANTS

The study uses an example based on hypothetical data on systolic blood pressure (SBP) from 25,000 people living in 39 neighbourhoods. As the focus is on the empty MLRA model, the study does not use any independent variable but focuses mainly on SBP variance between people and between neighbourhoods.

RESULTS

The intraclass correlation (ICC = 0.08) informed of an appreciable clustering of individual SBP within the neighbourhoods, showing that 8% of the total individual differences in SBP occurred at the neighbourhood level and might be attributable to contextual neighbourhood factors or to the different composition of neighbourhoods.

CONCLUSIONS

The statistical idea of clustering emerges as appropriate for quantifying "contextual phenomena" that is of central relevance in social epidemiology. Both concepts convey that people from the same neighbourhood are more similar to each other than to people from different neighbourhoods with respect to the health outcome variable.

Broken guide wire - a fault of design?

PURPOSE

To report a potentially serious complication resulting from a faulty guide wire during central venous catheterization.

CLINICAL FEATURES

We report breakage of a guide wire with potential severe implications for a 47-yr-old critical care patient. The tip of the J-wire became lodged in the internal jugular vein, and required fluoroscopic guidance for removal, which occurred without complication.

CONCLUSION

Breakage of a guide wire during central venous catheter insertion has been very rarely reported. However, inherent faults in design or in the manufacturing process of the guide wire could lead to this rare complication. A simple bedside test is proposed to detect breakage in the core section of the guide wire.