Temporal changes in the risk of six-month post-covid symptoms: a national population-based cohort study.

It is unclear how the risk of post-covid symptoms evolved during the pandemic, especially before the spread of Severe Acute Respiratory Syndrome Coronavirus 2 variants and the availability of vaccines. We used modified Poisson regressions to compare the risk of six-month post-covid symptoms and their associated risk factors according to the period of first acute covid: during the French first (March-May 2020) or second (September-November 2020) wave. Non-response weights and multiple imputation were used to handle missing data. Among participants aged 15 or more in a national population-based cohort, the risk of post-covid symptoms was 14.6% (95% CI: 13.9%, 15.3%) in March-May 2020, versus 7.0% (95% CI: 6.3%, 7.7%) in September-November 2020 (adjusted RR: 1.36, 95% CI: 1.20, 1.55). For both periods, the risk was higher in the presence of baseline physical condition(s), and it increased with the number of acute symptoms. During the first wave, the risk was also higher for women, in the presence of baseline mental condition(s), and it varied with educational level. In France in 2020, the risk of six-month post-covid symptoms was higher during the first than the second wave. This difference was observed before the spread of variants and the availability of vaccines.

Combined influence of immigration status and income on cervical cancer screening uptake.

The regular performance of Pap tests for cervical cancer screening reduces this disease's incidence and mortality. Income inequalities have been reported for this screening, partly because in some countries women must advance or even pay out-of-pocket costs. Because immigrant status is also associated with low Pap test uptake, we aimed to analyze the combined impact of immigrant status and low income on cervical cancer underscreening. This study, based on the French CONSTANCES cohort, uses data from the cohort questionnaires and linked health insurance fund data about Pap test reimbursement. To measure income inequalities in screening, we calculated a Slope Index of Inequality (SII) by linear regression, taking into account the migration status of participants. The majority of the 70,614 women included in the analysis were not immigrants (80.2%), while 12.9% were second-generation immigrants, and 6.9% first-generation immigrants. The proportion of underscreening increased with immigrant status, from 19.5% among nonimmigrants to 23.6% among the second generation, and 26.5% among the first (P < 0.01). The proportion of underscreening also increased as income level decreased. The income gradient rose significantly from 14% among nonimmigrants to 21% in second-generation immigrants and 19% in the first generation (P < 0.01). Among first-generation migrants, the shorter the duration of residence, the higher the SII. Women who are first- or second-generation immigrants are simultaneously underscreened and subject to a more unfavorable economic gradient than native French women born to native French parents. The accumulation of several negative factors could be particularly unfavorable to screening uptake.

When Lack of Trust in the Government and in Scientists Reinforces Social Inequalities in Vaccination Against COVID-19.

Objective: To assess whether lack of trust in the government and scientists reinforces social and racial inequalities in vaccination practices. Design: A follow-up of the EpiCov random population-based cohort survey. Setting: In July 2021, in France. Participants: Eighty-thousand nine hundred and seventy-one participants aged 18 years and more. Main Outcome Measures: Adjusted odds ratios of COVID-19 vaccination status (received at least one dose/ intends to get vaccinated/ does not know whether to get vaccinated/refuses vaccination) were assessed using multinomial regressions to test associations with social and trust factors and to study how these two factors interacted with each other. Results: In all, 72.2% were vaccinated at the time of the survey. The population of unvaccinated people was younger, less educated, had lower incomes, and more often belonged to racially minoritized groups, as compared to vaccinated people. Lack of trust in the government and scientists to curb the spread of the epidemic were the factors most associated with refusing to be vaccinated: OR = 8.86 (7.13 to 11.00) for the government and OR = 9.07 (7.71 to 10.07) for scientists, compared to vaccinated people. Lack of trust was more prevalent among the poorest which consequently reinforced social inequalities in vaccination. The poorest 10% who did not trust the government reached an OR of 16.2 (11.9 to 22.0) for refusing to be vaccinated compared to the richest 10% who did. Conclusion: There is a need to develop depoliticised outreach programmes targeted at the most socially disadvantaged groups, and to design vaccination strategies conceived with people from different social and racial backgrounds to enable them to make fully informed choices.

Trends in social exposure to SARS-Cov-2 in France. Evidence from the national socio-epidemiological cohort-EPICOV.

BACKGROUND: We aimed to study whether social patterns of exposure to SARS-CoV-2 infection changed in France throughout the year 2020, in light to the easing of social contact restrictions. METHODS: A population-based cohort of individuals aged 15 years or over was randomly selected from the national tax register to collect socio-economic data, migration history, and living conditions in May and November 2020. Home self-sampling on dried blood was proposed to a 10% random subsample in May and to all in November. A positive anti-SARS-CoV-2 ELISA IgG result against the virus spike protein (ELISA-S) was the primary outcome. The design, including sampling and post-stratification weights, was taken into account in univariate and multivariate analyses. RESULTS: Of the 134,391 participants in May, 107,759 completed the second questionnaire in November, and respectively 12,114 and 63,524 were tested. The national ELISA-S seroprevalence was 4.5% [95%CI: 4.0%-5.1%] in May and 6.2% [5.9%-6.6%] in November. It increased markedly in 18-24-year-old population from 4.8% to 10.0%, and among second-generation immigrants from outside Europe from 5.9% to 14.4%. This group remained strongly associated with seropositivity in November, after controlling for any contextual or individual variables, with an adjusted OR of 2.1 [1.7-2.7], compared to the majority population. In both periods, seroprevalence remained higher in healthcare professions than in other occupations. CONCLUSION: The risk of Covid-19 infection increased among young people and second-generation migrants between the first and second epidemic waves, in a context of less strict social restrictions, which seems to have reinforced territorialized socialization among peers.

Social inequalities and dynamics of the early COVID-19 epidemic: a prospective cohort study in France.

OBJECTIVE: Although social inequalities in COVID-19 mortality by race, gender and socioeconomic status are well documented, less is known about social disparities in infection rates and their shift over time. We aim to study the evolution of social disparities in infection at the early stage of the epidemic in France with regard to the policies implemented. DESIGN: Random population-based prospective cohort. SETTING: From May to June 2020 in France. PARTICIPANTS: Adults included in the Epidémiologie et Conditions de Vie cohort (n=77 588). MAIN OUTCOME MEASURES: Self-reported anosmia and/or ageusia in three categories: no symptom, during the first epidemic peak (in March 2020) or thereafter (during lockdown). RESULTS: In all, 2052 participants (1.53%) reported anosmia/ageusia. The social distribution of exposure factors (density of place of residence, overcrowded housing and working outside the home) was described. Multinomial regressions were used to identify changes in social variables (gender, class and race) associated with symptoms of anosmia/ageusia. Women were more likely to report symptoms during the peak and after. Racialised minorities accumulated more exposure risk factors than the mainstream population and were at higher risk of anosmia/ageusia during the peak and after. By contrast, senior executive professionals were the least exposed to the virus with the lower rate of working outside the home during lockdown. They were more affected than lower social classes at the peak of the epidemic, but this effect disappeared after the peak. CONCLUSION: The shift in the social profile of the epidemic was related to a shift in exposure factors under the implementation of a stringent stay-at-home order. Our study shows the importance to consider in a dynamic way the gender, socioeconomic and race direct and indirect effects of the COVID-19 pandemic, notably to implement policies that do not widen health inequalities.

Social inequalities in participation in cancer screening: does the mode of data collection matter? The CONSTANCES cohort.

BACKGROUND: Self-reported data are prone to item non-response and misreporting. We investigated to what extent the use of self-reported data for participation in breast (BCS) and cervical cancer screening (CCS) impacted socioeconomic inequalities in cancer screening participation. METHODS: We used data from a large population-based survey including information on cancer screening from self-reported questionnaire and administrative records (n = 14 122 for BCS, n = 27 120 CCS). For educational level, occupation class and household income per capita, we assessed the accuracy of self-reporting using sensitivity, specificity and both positive and negative predictive value. In addition, we estimated to what extent the use of self-reported data modified the magnitude of socioeconomic differences in BCS and CCS participation with age-adjusted non-screening rate difference, odds ratios and relative indices of inequality. RESULTS: Although women with a high socioeconomic position were more prone to report a date for BCS and CCS in questionnaires, they were also more prone to over-declare their participation in CCS if they had not undergone a screening test within the recommended time frame. The use of self-reported cancer screening data, when compared with administrative records, did not impact the magnitude of social differences in BCS participation but led to an overestimation of the social differences in CCS participation. This was due to misreporting rather than to item non-response. CONCLUSIONS: Women's socioeconomic position is associated with missingness and the accuracy of self-reported BCS and CCS participation. Social inequalities in cancer screening participation based on self-reports are likely to be overestimated for CCS.

When lockdown policies amplify social inequalities in COVID-19 infections: evidence from a cross-sectional population-based survey in France.

BACKGROUND: Significant differences in COVID-19 incidence by gender, class and race/ethnicity are recorded in many countries in the world. Lockdown measures, shown to be effective in reducing the number of new cases, may not have been effective in the same way for all, failing to protect the most vulnerable populations. This survey aims to assess social inequalities in the trends in COVID-19 infections following lockdown. METHODS: A cross-sectional survey conducted among the general population in France in April 2020, during COVID-19 lockdown. Ten thousand one hundred one participants aged 18-64, from a national cohort who lived in the three metropolitan French regions most affected by the first wave of COVID-19. The main outcome was occurrence of possible COVID-19 symptoms, defined as the occurrence of sudden onset of cough, fever, dyspnea, ageusia and/or anosmia, that lasted more than 3 days in the 15 days before the survey. We used multinomial regression models to identify social and health factors related to possible COVID-19 before and during the lockdown. RESULTS: In all, 1304 (13.0%; 95% CI: 12.0-14.0%) reported cases of possible COVID-19. The effect of lockdown on the occurrence of possible COVID-19 was different across social hierarchies. The most privileged class individuals saw a significant decline in possible COVID-19 infections between the period prior to lockdown and during the lockdown (from 8.8 to 4.3%, P = 0.0001) while the decline was less pronounced among working class individuals (6.9% before lockdown and 5.5% during lockdown, P = 0.03). This differential effect of lockdown remained significant after adjusting for other factors including history of chronic disease. The odds of being infected during lockdown as opposed to the prior period increased by 57% among working class individuals (OR = 1.57; 95% CI: 1.00-2.48). The same was true for those engaged in in-person professional activities during lockdown (OR = 1.53; 95% CI: 1.03-2.29). CONCLUSIONS: Lockdown was associated with social inequalities in the decline in COVID-19 infections, calling for the adoption of preventive policies to account for living and working conditions. Such adoptions are critical to reduce social inequalities related to COVID-19, as working-class individuals also have the highest COVID-19 related mortality, due to higher prevalence of comorbidities.

Women with obesity in cervical cancer screening. The double penalty: Underscreening and income inequalities.

The regular performance of Pap tests reduces the mortality of cervical cancer. Obesity is associated with low Pap test rates. We analyze the combined role of obesity and low income. We calculated a Slope Index of Inequality. Among the 28,905 women included, 23.1% were underscreened. The rate of underscreening increased with BMI. The income gradient increased significantly from 0.17 among normal-weight women to 0.19 in overweight and 0.23 in obese women (p = 0.047). Women who are obese are subject to a double penalty in cervical cancer screening: they are underscreened and subject to a more unfavorable economic gradient than normalweight women.

Patterns of gynaecological check-up and their association with body mass index within the CONSTANCES cohort.

OBJECTIVES: To investigate the relationship between patterns of gynaecological check-up and body mass index while accounting for various determinants of health care use. METHODS: Sequence analysis and clustering were used to highlight patterns of gynaecological check-up, which included the regularity of breast and cervical cancer screening and visits to the gynaecologist over four years, among 6182 women aged 54-65 included in the CONSTANCES cohort between 2013 and 2015 in France. Multinomial logistic regressions were used to study the association between these patterns and women's body mass index. RESULTS: We identified four patterns of gynaecological check-up, from (A) no or inappropriate check-up (20%) to (D) almost one visit to the gynaecologist every year, overscreening for cervical cancer and frequent use of opportunistic breast cancer screening (12%). From patterns A to D, the proportion of obese women decreased and that of women with normal body mass index increased. Obese and overweight women underwent more breast than cervical cancer screening and were less often overscreened than normal weight women. These differences were only partly explained by the lower socioeconomic situation of overweight and obese women. Beyond the financial barrier, the screening modality and the type of exam may play a role. Among women who were screened for cervical cancer, obese and overweight women were less often screened by a gynaecologist. CONCLUSION: Further efforts should be made to enhance the take-up of screening among obese women who are deterred by the healthcare system.

The role of prenatal social support in social inequalities with regard to maternal postpartum depression according to migrant status.

BACKGROUND: An advantaged socioeconomic position (SEP) and satisfying social support during pregnancy (SSP) have been found to be protective factors of maternal postpartum depression (PDD). An advantaged SEP is also associated with satisfying SSP, making SSP a potential mediator of social inequalities in PPD. SEP, SSP and PPD are associated with migrant status. The aim of this study was to quantify the mediating role of SSP in social inequalities in PPD regarding mother's migrant status. METHODS: A sub-sample of 15,000 mothers from the French nationally-representative ELFE cohort study was used for the present analyses. SEP was constructed as a latent variable measured with educational attainment, occupational grade, employment, financial difficulties and household income. SSP was characterized as perceived support from partner (good relation, satisfying support and paternal leave) and actual support from midwives (psychosocial risk factors assessment and antenatal education). Mediation analyses with multiple mediators, stratified by migrant status were conducted. RESULTS: Study population included 76% of non-migrant women, 12% of second and 12% of first generation migrant. SEP was positively associated with support from partner, regardless of migrant status. Satisfying partner support was associated with a 8 (non-migrant women) to 11% (first generation migrant women) reduction in PPD score. LIMITATIONS: History of depression was not reported. CONCLUSIONS: Partner support could reduce social inequalities in PPD. This work supports the need of interventions, longitudinal and qualitative studies including fathers and adapted to women at risk of PPD to better understand the role of SSP in social inequalities in PPD.

Combined Effect of Health Status and Primary Care Use on Participation in Cancer Screening: The CONSTANCES Cohort.

Background: The combined association between primary care utilization and health status with breast cancer screening (BCS) and cervical cancer screening (CCS) remains unclear. Our aim was to identify women's profiles based on their health status and primary care utilization and study their associated adherence to BCS and CCS recommendations. Methods: Using data from the cohort of people visiting health screening centers (CONSTANCES) in France (2012-2015), we first identified women's profiles based on their health status (self-perceived health, physical, and mental health) and primary care utilization (visit to the General Practitioner [GP], uptake of blood tests) using a multiple correspondence analysis and a hierarchical cluster analysis. We then investigated the association of these profiles to BCS and CCS using logistic regression models adjusted for age, smoking status, sociodemographic and socioeconomic characteristics, and the regularity of gynecologist consultation. Results: We identified five distinct profiles of women with contrasted participation in BCS (n = 14,122) and CCS (n = 27,120). In multivariate analyses, cancer screening participation increased from women with very good health and poor primary care utilization, to those with poor health and frequent visits to the GP, and those with very good health and average primary care utilization. The most favorable profiles regarding cancer screening rates were women with average-to-poor health and regular visits to the GP and uptake of blood tests. Conclusions: Our results suggest that policies aiming at increasing cancer screening participation should simultaneously account for women's use of primary care and health and consider more specific subgroups than what is usually done. Further research should investigate factors motivating cancer screening practice, such as women's beliefs regarding cancer screening and women's psychological characteristics.

The determinants of cervical cancer screening uptake in women with obesity: application of the Andersen's behavioral model to the CONSTANCES survey.

PURPOSE: Despite their higher risk for and mortality from cervical cancer, evidence indicates low rates of cervical cancer screening (CCS) among women with obesity. The literature on the specific factors related to CCS nonadherence in this population is limited. METHODS: We examined the data on 2,934 women with obesity included in the CONSTANCES survey from 2012 to 2015. Using the Andersen's behavioral model, we studied the relationships between the socioeconomic, sociodemographic, health, health personal behaviors, and healthcare use-related factors with CCS nonadherence. The analysis was performed using structural equation models. RESULTS: Regular follow-up by a gynecologist, good quality of primary care follow-up, and comorbidities were negatively associated with CCS nonadherence. Limited literacy, older age, being single, living without children, and financial strain were positively associated with CCS nonadherence. Our results do not point to competitive care, since women with comorbidities had better CCS behaviors, which were explained by a good quality of primary care follow-up. CONCLUSION: Our study identified the factors that explain CCS nonadherence among women with obesity and clarified the effects of health status and healthcare use on screening. Further efforts should be undertaken to reduce the obstacles to CCS by improving care among women with obesity.

Role of obesity in differences in cervical cancer screening rates by migration history. The CONSTANCES survey.

BACKGROUND: Immigrant women often have lower cervical cancer screening (CCS) rates, tend to have a higher body mass index (BMI) and may be more vulnerable to BMI-related stigmatization. Our aim was to assess the role of BMI in differences in CCS rates by migration history. METHODS: Analyses were based on the 2012-2015 inclusion data (n = 27,226) for the population-based CONSTANCES cohort, including detailed, self-reported information on demographics and socioeconomic characteristics, migration history, health behaviours, health, and health care use. Measured BMI (underweight (<18.5), normal-weight (18.5-25), overweight (25-30), obese (>30)) was collected. Poisson regression models with robust variance were conducted to assess the contribution of BMI to differences in CCS rates by migration history, and analyses stratified by BMI were done. Multiple imputations were performed. RESULTS: The CCS rates ranged from 87% among French-born women with two French parents to 86% among French-born women with at least one parent of foreign origin, 82% among naturalized immigrants and 74% among non-naturalized immigrants. After adjusting for covariates, non-naturalized immigrants showed an 11% (95% CI: 8%-14%) lower CCS rate than French-born women with two French parents. Adjusting for BMI did not change the estimates. When stratifying by BMI category, non-naturalized immigrants showed an 11% (7%-14%) lower CCS rate then French-born with two French parents when normal weight, a 9% (2%-16%) lower CCS rate when overweight, and an 18% (5%-30%) lower CCS rate when obese. CONCLUSION: Migration history and BMI jointly impact CCS rates. They were lower among all non-naturalized immigrants, particularly those who were obese.

Occupational prestige trajectory and the risk of lung and head and neck cancer among men and women in France.

OBJECTIVES: This study aimed at investigating the associations between occupational prestige trajectories and lung and head and neck (HN) cancer risk and to assess to what extent smoking, alcohol drinking, and occupational exposures contribute to these associations. METHODS: Using data from the ICARE case-control study (controls (2676 men/715 women), lung cancers (2019 men/558 women), HN cancers (1793 men/305 women), we defined occupational prestige trajectories using group-based modeling of longitudinal data. We conducted logistic regression models. RESULTS: Among men, a gradient was observed from the downward "low to very low" trajectory to the stable very high trajectory. The associations were reduced when adjusting for tobacco and alcohol consumption and occupational exposures. Among women, when compared to the stable high trajectory, there was an increased cancer risk in all trajectories. The associations remained globally unchanged or even increased after adjustment for tobacco and alcohol consumption and did not change when adjusting for occupational exposures. The ORs were smaller for lung than for HN cancers in men. CONCLUSIONS: Occupational prestige trajectory is strongly associated with lung and HN cancer risk in men and women.

Contextual determinants of participation in cervical cancer screening in France, 2010.

BACKGROUND: Some contextual factors associated with participation in cervical cancer screening are reported in the literature, but few studies have examined their combined effect. Our objective was to assess the role of contextual characteristics, separately and in combination, in participation in cervical cancer screening in France. METHODS: Marginal Poisson regression models - taking into account the correlation between women in a given commune - were conducted using data from the Baromètre Santé 2010 survey. The characteristics of the commune of residence of the women studied were the potential spatial accessibility to general practitioners (GP) and gynecologists, the agglomeration category, and the socioeconomic level. RESULTS: The analyses were performed in 3380 women, 88.2% of whom were up to date with their cervical cancer screening. Once the individual characteristics were taken into account, the screening participation rate was similar in all the communes, with the exception of those with poor access to a gynecologist and good access to a GP, where the rate was 6% lower (95%CI: 0.5-11%) than in the communes with good access to both GP and gynecologist. The same association with accessibility was observed in small agglomerations. Compared to women living in the more advantaged communes, the screening participation rate was 8% (2-12%) lower in those living in the more disadvantaged ones, except when accessibility to both types of physician was high. DISCUSSION: We observed an association between potential spatial accessibility to care in women's residential communities and their cervical cancer screening practices, in particular in small agglomerations, rural communes, and more disadvantaged communes.

Quantifying the mediating effects of smoking and occupational exposures in the relation between education and lung cancer: the ICARE study.

Smoking only partly explains the higher lung cancer incidence observed among socially deprived people. Occupational exposures may account for part of these inequalities, but this issue has been little investigated. We investigated the extent to which smoking and occupational exposures to asbestos, silica and diesel motor exhaust mediated the association between education and lung cancer incidence in men. We analyzed data from a large French population-based case-control study (1976 lung cancers, 2648 controls). Detailed information on lifelong tobacco consumption and occupational exposures to various carcinogens was collected. We conducted inverse probability-weighted marginal structural models. A strong association was observed between education and lung cancer. The indirect effect through smoking varied by educational level, with the strongest indirect effect observed for those with the lowest education (OR = 1.34 (1.14-1.57)). The indirect effect through occupational exposures was substantial among men with primary (OR = 1.22 (1.15-1.30) for asbestos and silica) or vocational secondary education (OR = 1.18 (1.12-1.25)). The contribution of smoking to educational differences in lung cancer incidence ranged from 22 % (10-34) for men with primary education to 31 % (-3 to 84) for men with a high school degree. The contribution of occupational exposures to asbestos and silica ranged from 15 % (10-20) for men with a high school degree to 20 % (13-28) for men with vocational secondary education. Our results highlight the urgent need for public health policies that aim at decreasing exposure to carcinogens at work, in addition to tobacco control policies, if we want to reduce socioeconomic inequalities in the cancer field.

Hemodiafiltration Versus Hemodialysis and Survival in Patients With ESRD: The French Renal Epidemiology and Information Network (REIN) Registry.

BACKGROUND: Recent randomized trials report that mortality is lower with high-convection-volume hemodiafiltration (HDF) than with hemodialysis (HD). STUDY DESIGN: We used data from the French national Renal Epidemiology and Information Network (REIN) registry to investigate trends in HDF use and its relationship with mortality in the total population of incident dialysis patients. SETTING & PARTICIPANTS: The study included those who initiated HD therapy from January 1, 2008, through December 31, 2011, and were dialyzed for more than 3 months; follow-up extended to the end of 2012. FACTOR: HDF use at the patient and facility level. OUTCOMES: All-cause and cardiovascular mortality, using Cox models to estimate HRs of HDF as time-dependent covariate at the patient level, with age as time scale and fully adjusted for comorbid conditions and laboratory data at baseline, catheter use, and facility type as time-dependent covariates. Analyses completed by Cox models for HRs of the facility-level exposure to HDF updated yearly. RESULTS: Of 28,407 HD patients, 5,526 used HDF for a median of 1.2 (IQR, 0.9-1.9) years; 2,254 of them used HDF exclusively. HRs for all-cause and cardiovascular mortality associated with HDF use were 0.84 (95% CI, 0.77-0.91) and 0.73 (95% CI, 0.61-0.88), respectively. In patients treated exclusively with HDF, these HRs were 0.77 (95% CI, 0.67-0.87) and 0.66 (95% CI, 0.50-0.86). At the facility level, increasing the percentage of patients using HDF from 0% to 100% was associated with HRs for all-cause and cardiovascular mortality of 0.87 (95% CI, 0.77-0.99) and 0.72 (95% CI, 0.54-0.96), respectively. LIMITATIONS: Observational study. CONCLUSIONS: Whether analyzed as a patient- or facility-level predictor, HDF treatment was associated with better survival.

Improved survival associated with acetate-free haemodialysis in elderly: a registry-based study.

BACKGROUND: Acetate-free dialysis (AFD) improves haemodynamic stability during dialysis, compared with standard haemodialysis (HD) with a small amount of acetic acid. Using the national REIN registry, we classified 15 160 incident patients who started HD from 2008 to 2010 into three exposure categories according to the type of dialysate used in their dialysis unit: standard dialysate only (reference), both standard and AFD (mixed unit) or HCl dialysate only (100% HCl unit). METHODS: Cox survival analysis was adjusted for 15 baseline comorbidities, laboratory data and haemodiafiltration (HDF). We took patient clustering within units into account, used age as the time scale and treated patient exposure to AFD and to HDF as time-dependent variables. RESULTS: Median age (interquartile range) was 70.5 years (58.1-78.8). Over a median follow-up of 1.8 years (1.2-2.6), 658 patients were dialysed in a 100% HCl unit, 3021 in a mixed unit and 11 481 were never exposed to AFD. The relation between AFD and mortality was not constant with age (Schoenfeld residuals test P = 0.01 for mixed group and P = 0.03 for 100%HCl group). Patients older than 70 years had a significantly lower mortality risk associated with AFD [hazard ratio (HR) = 0.79, 95% confidence interval (CI) = 0.67 to 0.94 for patients exposed in a 100% HCl unit; HR = 0.83, 95% CI = 0.74 to 0.94 for patients exposed in a mixed unit], but no association was found in younger patients. CONCLUSIONS: AFD was associated with improved survival independent of comorbidities and HDF in patients aged 70 years and older but not in patient younger than 70 years.