Phenotyping chronic respiratory diseases with airways obstruction.

Given the high prevalence of asthma-chronic obstructive pulmonary disease overlap (ACO) in Vietnam, there is an urgent need to establish a simplified strategy for categorising patients as either having asthma or chronic obstructive pulmonary disease (COPD). This classification would streamline the application of treatment recommendations outlined by the Global Initiative for Asthma (GINA) and the Global Initiative for Chronic Obstructive Lung Disease (GOLD).Patients with obstructive lung function were classified as having COPD, asthma, or ACO based on GINA/GOLD guidelines. We hypothesised that ACO-like asthma (ACO-A) would present with positive skin prick tests (SPTs) or early onset of symptoms without a history of tuberculosis (TB), while those with ACO-like COPD (ACO-B) would exhibit negative SPTs and late onset of symptoms and/or a history of TB.Among 235 patients, the prevalence of asthma, ACO-A, ACO-B, and COPD was respectively 21%, 22%, 17%, and 40%. Allergic history, rhinitis, and childhood asthma were associated with ACO-A, while high cumulative smoking was correlated with ACO-B. Socio-economic and demographic parameters, medical history, clinical features, smoking habits, lung function, and para-clinical investigations significantly differed between "all asthma" (i.e., individuals with asthma combined with ACO-A) and "all COPD" (i.e., individuals with COPD combined with ACO-B).Based on SPTs, history of TB, and onset age, ACO patients may be defined as people with asthma or COPD..

[Professional profiles and representations of staff members in Burundi health centers: Socio-professional groups with compartmentalizes knowledge]. / Profils et représentations professionnelles des agents en centre de santé au Burundi : des groupes socio-professionnels aux savoirs cloisonnés.

BACKGROUND: The professional identities, profiles and representations of Burundian health workers remain insufficiently explored. Our twofold objective is to identify the different socio-professional profiles of first-line caregivers and to explore their respective representations of health workers and work. METHODS: The first study describes the overall population of the 1047 staff members employed in 2014-2015 in 62 health centers. The second is a cross-sectional survey conducted in April 2014. Using IRAMUTEQ© software, we conducted textology analysis of the structure and contents of 911 respondents' representations via 3 free associations with regard to 6 questions on the "good worker" and the "what renders one capable of doing good work". RESULTS: At the normative level, among all categories of staff, a relational role is a foundation of professional identity, while technical or administrative functions remain marginal. At the positional level, responses differed according to initial qualification level but not as a function of their role with patients or their professional experience. Three socio-professional categories emerged. The most qualified category (one-quarter of the population) consists primarily of male caregivers, with a high turnover rate (4 years) associated with prospects for further training and career development. These persons present the most professionalized representations of the worker and work. The second quarter has an average level of qualification and turnover (10 years), and is mainly composed of female caregivers with limited professional perspectives. This group's representations are less technical and more patient-centered. Finally, the remaining half consists of relatively low-skilled staff members in charge of technical and logistical support, who are likely to spend their entire career in the same center (>20 years). Largely disregarded by the health care system and its funders, they have few opportunities for training or advancement and despite their long experience, maintain profane representations of workers and work. CONCLUSION: Our results shed light on the predicament of unskilled staff members whose expectations are rarely taken into consideration, even though they represent a significant proportion of the workforce, perform tasks essential to quality of care, and serve as bearers of the memory of their hospital center. These results also highlight the compartmentalization of practices and knowledge between categories of workers and underscore the failure of continuous training strategies targeting the unskilled.

Influence of type of dwelling on the prevalence of chronic respiratory diseases in Ho Chi Minh City, Viet Nam.

SETTING and OBJECTIVE: Exposure to pollutants is related to the type of dwelling inhabited. Besides tobacco smoke, indoor air pollution is a significant risk factor for chronic respiratory disease (CRD). The prevalence of CRD by type of dwelling was studied in Ho Chi Minh City, Viet Nam.DESIGN: A total of 1561 people living in four type of dwellings were enrolled. Information on respiratory health, lung function, dwelling characteristics and sources of indoor pollution was obtained using a symptom and demographics questionnaire and spirometry. The two main respiratory health outcomes were clinical chronic CRD (CCRD) and chronic obstructive respiratory disease (CORD) (forced expiratory volume in 1 sec/forced vital capacity <0.7). We used binary logistic regression adjusted for age, sex, time spent at home, smoking status, certain occupational exposures, previous tuberculosis, presence of pets, rats or cockroaches at home, wall dampness, biofuel use and use of airconditioning.RESULTS: The prevalence of CCRD (24.3%) and CORD (5.3%) in the type of dwellings studied were not similar (χ² P < 0.0001). CCRD and CORD prevalence was similar in tube houses and apartments. Compared to people living in apartments, those living in rental single rooms had a 46% higher risk of developing CCRD. The odds ratio of having CORD in people living in rental single rooms and in rural houses were respectively 4.64 (95%CI 1.97-10.5) and 2.99 (95%CI 1.21-7.37).CONCLUSION: Type of dwelling was associated with CCRD and CORD morbidity.

Immigration and adolescent health: the case of a multicultural population.

OBJECTIVES: Previous research indicates that the impact of immigration on health tends to be specific as it is influenced by many factors such as life stage and host country. The aim of this study was to examine the relationship between immigration and adolescent health within the multicultural context of the Brussels-Capital Region in Belgium. STUDY DESIGN: The study was based on the 2014 Health Behaviour in School-aged Children survey. The sample consisted of 2962 adolescents from the fifth grade of primary to the last grade of secondary schools in Brussels. METHODS: Associations between health indicators and immigration status were analysed using multivariable logistic regression models adjusted for sociodemographic characteristics. RESULTS: Natives, first-generation immigrants, second-generation immigrants with both parents born abroad and second-generation immigrants with one parent born abroad represented 19%, 23%, 36% and 22% of the respondents, respectively. Sociodemographic characteristics and health behaviours varied according to immigrant status. Young immigrants were more likely to present overweight (odds ratio [OR] first-generation immigrants vs. natives = 1.76 [95% confidence interval {CI} = 1.16-2.65]; OR second-generation immigrants with both parents born abroad vs. natives = 2.06 [95% CI = 1.41-3.02]; OR second-generation immigrants with one parent born abroad vs. natives = 1.69 [95% CI = 1.12-2.56]). This effect turned out to be partially explained by sociodemographic status and health-related behaviours. No association was detected between immigration and self-rated health and multiple recurrent symptoms. CONCLUSIONS: Discrepancies in health behaviours and weight status were identified between adolescents of different immigration background, whereas this was not the case for well-being. Socio-economic status, cultural characteristics and specific behaviours partly explained these findings. Future research is needed to better understand immigration-related risk and protective factors, at individual and school levels.

Accessibility of cesarean deliveries in Benin.

To be used effectively, emergency obstetric and neonatal care must be available and accessible. This study sought to measure the accessibility of cesarean deliveries in Benin. Cross-sectional study of randomly selected women in each of the 12 obstetrics departments in Benin. Geographical accessibility was measured by estimating the distance between the parturientes residence and the hospital. Financial accessibility was the average direct cost of the cesarean delivery -the sum of medical and non-medical costs. The functionality of the referral system was assessed according to the conditions of referral of women referred for cesareans. The mean distance between women's homes and the hospital was 20.2 ± 22.3 kilometers. Of the 579 women, 63.0 % were referred from a peripheral health center to a hospital; the referral conditions were completed in the obstetric record for only half of them. The data sheet for the referral was completed for only 34.4 %; venous access had been placed in 28.5 %, and the patient was accompanied by medical personnel in only 1.7% of cases. The average direct cost of the cesarean to families was 36,782 ± 30,859 FCFA. Cesarean deliveries are now more accessible financially due to the policy of free access, but they remains geographically inaccessible, because of the long distances to be covered and the poor organization of referrals to ensure continuity of care.

Allergen sensitisation among chronic respiratory diseases in urban and rural areas of the south of Viet Nam.

OBJECTIVE: To evaluate the prevalence of and risk factors for allergen sensitisation among patients with chronic respiratory disease (CRD) in southern Viet Nam. DESIGN: An environmental questionnaire and skin prick tests for airborne and food allergens were administered to patients with CRD, defined as individuals with respiratory symptoms and lung function defects. RESULTS: Of 610 CRD patients, 56% had chronic obstructive pulmonary disease and 31% were asthma patients; 80% were males. The most frequent sensitisers were dust mites (Dermatophagoides farinae 22%, Blomia tropicalis 19%, D. pteronyssinus 18%) and cockroach droppings (13%). Among study participants, 37% were from rural settings and 36% from urban areas, whereas 27% had migrated from rural to urban areas. Compared with people from rural areas, being born in an urban area was a risk factor for sensitisation to mites (OR 1.56, 95%CI 1.11-2.20, P < 0.02). In multivariate analysis, place of birth remained a risk factor for mite sensitisation. Compared with the native urban population, the risk of mite sensitisation was not significantly different among patients born in rural areas and those migrating to urban areas. CONCLUSION: Dust mites and cockroach droppings were the most frequent allergens among people with CRD in the south of Viet Nam. Compared with the urban population, being native to a rural area was protective against mite sensitisation, but this effect ceased to be significant after migration from rural to urban areas.

Predictors of past quit attempts and duration of abstinence among cigarette smokers.

OBJECTIVE: Despite the widespread awareness of the harms of smoking, millions continue to smoke around the world partly due to the difficulty it takes to quit smoking. Identifying the factors associated with making quit attempts is an essential pillar to reach successful quitting. The purpose of this study is to assess the factors associated with the past quit attempts and their past length of abstinence in a Lebanese sample of cigarette smokers. METHODS: This study was conducted between March 2014 and March 2015, involving 382 patients randomly chosen from 5 outpatient clinics in 5 hospitals in Lebanon. A standardized questionnaire was completed including socio-demographic characteristics, smoking behavior, chronic respiratory symptoms, Fagerstrom scale, Mondor scale, packaging perception, quitting behavior and readiness to quit ladder. RESULTS: Smokers who have chronic allergies (ORa=2.45, p=0.03), those who have ever stopped smoking for at least one month due to the warnings implemented on the packages (ORa=4.6, p<0.0001) and smokers with an intention to quit in 2months (ORa=2.49, p<0.0001) had significantly more past quit attempts. Furthermore, longer quit attempts duration (more than 1month) were significantly associated with low-nicotine dependent smokers (ORa=0.56, p=0.02), higher-motivated smokers (ORa=1.85, p=0.01), people with chronic allergies (ORa=2.07, p=0.02), smokers who have ever stopped smoking for at least one month due to the warnings (ORa=3.72, p<0.0001) and those with an intention to quit in 2months (ORa=1.98, p=0.05). CONCLUSION: The promoters of smoking cessation services should consider these factors when designing comprehensive tobacco control initiatives and in service planning.

Overnight improvements in two REM sleep-sensitive tasks are associated with both REM and NREM sleep changes, sleep spindle features, and awakenings for dream recall.

Memory consolidation is associated with sleep physiology but the contribution of specific sleep stages remains controversial. To clarify the contribution of REM sleep, participants were administered two REM sleep-sensitive tasks to determine if associated changes occurred only in REM sleep. Twenty-two participants (7 men) were administered the Corsi Block Tapping and Tower of Hanoi tasks prior to and again after a night of sleep. Task improvers and non-improvers were compared for sleep structure, sleep spindles, and dream recall. Control participants (N = 15) completed the tasks twice during the day without intervening sleep. Overnight Corsi Block improvement was associated with more REM sleep whereas Tower of Hanoi improvement was associated with more N2 sleep. Corsi Block improvement correlated positively with %REM sleep and Tower of Hanoi improvement with %N2 sleep. Post-hoc analyses suggest Tower of Hanoi effects-but not Corsi Block effects-are due to trait differences. Sleep spindle density was associated with Tower of Hanoi improvement whereas spindle amplitude correlated with Corsi Block improvement. Number of REM awakenings for dream reporting (but not dream recall per se) was associated with Corsi Block, but not Tower of Hanoi, improvement but was confounded with REM sleep time. This non-replication of one of 2 REM-sensitive task effects challenges both 'dual-process' and 'sequential' or 'sleep organization' models of sleep-dependent learning and points rather to capacity limitations on REM sleep. Experimental awakenings for sampling dream mentation may not perturb sleep-dependent learning effects; they may even enhance them.

Obesity and symptoms of depression among adults in selected countries of the Middle East: a systematic review and meta-analysis.

Although obesity has been widely recognized for its consequences on physical health, its psychological burden in the adult populations in the Middle East remains unclear. This meta-analysis synthesized data from observational studies to investigate the association between obesity and depression among adult populations in Middle Eastern countries. Five bibliographical electronic databases were searched for studies published up to April 2014. Pooled meta-analytic estimates were derived using the random-effect models. Three case-control studies and five cross-sectional studies were identified. Meta-analysis showed significant positive associations between obesity and depression across study designs, with an overall effect of odds ratio 1.27 (95% confidence interval 1.11-1.44). The association between obesity and depression was more marked in women than men although that difference was not statistically significant. Other subgroup analysis showed that none of the potential factors including the assessment for obesity or depression, confounder control and study quality had a modification effect on the studied association. Meta-analysis of eight observational studies from five countries in the Middle East suggests an evidence of a positive association between obesity and depression among adult populations, which appeared to be more marked among women. Future research should examine the causal pathways between obesity and depression.

[Qualitative analysis of the offer for prevention and caring of sickle cell anaemia in Brussels]. / Analyse qualitative de l'offre pour la prevention et la prise en charge de la drépanocytose à Bruxelles.

Sickle cell disease (SCD) is the first genetic disease in the world and remains largely ignored by the population but also by health professionals. SCD is characterized by a variable clinical expression, however most of the patients are at risk to develop acute and severe complications conducting to a fatal issue. This study develops a qualitative approach to analyze the adequacy between the services offered for those patients in Brussels and the sociocultural characteristics of the target population and more specifically of the migrant population originating of sub-saharan Africa which is the most concerned. To have a global vision of the preventive and care services provided for SCD in Brussels, semistructured interviews were conducted with health professionals and patients associations. The results were analyzed to determine if they match the expectations of health professionals and audiences across the voluntary sector. The results show the absence of a real recognition at the national level of sickle cell anaemia, a deficit in psychosocial care of patients and their families. SCD is often considered by the African community as a disease of the curse which has to be hidden. To the physical pain and multiple organ complications one must add a psychological distress that patients drive back into silence. The management of this disease therefore requires a dedicated approach. With the exception of newborn screening performed in all maternity hospitals in Brussels and Liège, there is no specific measure for the management of SCD in Belgium.

Working conditions predict incidence of long-term spells of sick leave due to depression: results from the Belstress I prospective study.

BACKGROUND: During the last few years, a high incidence of sick leave due to depression has been reported, resulting in important economic and social impacts. Only a limited number of studies investigating the influence of psychosocial working conditions on sick leave have been prospective and have utilised a valid methodology, while none have studied sick leave due to depression. In this study, the impact of adverse psychosocial working conditions is analysed on the risk for long-term sick leave due to depression. METHODS: This study resulted from the large-scale Belstress I study on the relationship between perceived job stress and health problems. Subjects were Belgian employees selected from 11 large companies (n = 9396). Using a longitudinal design, the association between the three Karasek stress dimensions (job control, psychological demand, and social support) was explored, separately and combined according to the demand-control and demand-control-support models and the incidence of long-term sick leave for depression as diagnosed by the family physician. RESULTS: After adjusting for age, occupational categories, living situation, and baseline depression score, 'passive jobs' (OR 2.67; 95% CI 1.15 to 6.19) and 'high strain' jobs (OR 3.23; 95% CI 1.40 to 7.43) predicted sick leave due to depression at follow-up in men. Job control predicted sick leave due to depression in both men (OR 2.43; 95% CI 1.27 to 4.66) and women (OR 2.21; 95% CI 1.05 to 4.68). CONCLUSIONS: This study provides evidence that the psychosocial working environment influences long-term sick leave due to depression. Efforts to improve skill discretion and decision authority at work could help prevent depression.

[A patient-centered approach to tuberculosis control in Burkina Faso]. / L'approche centrée sur le patient pour la lutte contre la tuberculose au Burkina Faso.

BACKGROUND: The Burkina Faso health system is divided into 55 health districts (DS), each with more than 10 primary care health centers (CSPS) that comprise the first level of the health care system. For this study, we chose two intervention districts (one rural, one urban) and two control districts. OBJECTIVE: To evaluate the impact of the patient-centered approach to tuberculosis control on the detection and treatment of tuberculosis. METHOD: This intervention, defined in a consensus process by various participants in tuberculosis management, was implemented in two districts (one rural and one urban). Study outcomes were measured before and after the intervention in two intervention districts and two control districts. RESULTS: The proportion of patients suspected of tuberculosis who chose sputum sampling in the CSPS was higher in the rural district (Gorom-Gorom) than in the urban one (Pissy): 46% versus 18.7% (p < 0.001). Detection improved more in the intervention than control districts (59% versus 20%). The increase in diagnosis was better in the intervention districts than in their matched control districts (46% versus 5% in the rural district; 75% versus 32% in the urban district). The treatment success rate was better in the rural district's decentralized CSPSs than in its CDTs (Gorom-Gorom) (61.8% vs 52.8%), while the reverse was true in the urban district (Pissy) (75% vs 83.1%). CONCLUSION: Detection of new tuberculosis cases increased throughout this study. Improvement in treatment regularity was limited. A longer intervention is needed to evaluate the effects of this approach on treatment results.

[Emergency obstetrical care in Benin referral hospitals: 'near miss' patients' views]. / La qualité de prise en charge des urgences obstétricales dans les maternités de référence au Bénin: le point de vue des "Echappées Belles" et leurs attentes.

OBJECTIVE: To evaluate emergency obstetric care and the perceptions and expectations of women who experienced 'near miss' events to improve maternal health in Benin. METHODS: Qualitative survey in seven hospitals at the three referral levels of the health pyramid from July to October 2003. We used two methods: 557 women with near miss events were interviewed in hospital and a standard questionnaire completed; then semi-structured individual interviews were conducted at home with 42 of these 557 women. RESULTS: Provided care, accommodation, facilities, costs and modalities of recovery, hygiene of the premises, dynamism, expertise, social support, behaviours and attitude of staff were the criteria used to express patients' satisfaction. Most women interviewed in hospital were happy with physical access, organization, functioning and environment. However, excessive costs and coercive recovery of the expenses, failure of the referral system, lack of empathy and discrimination of the nursing staff, lack of resources for emergencies, lack of hygiene and comfort of the premises were criticized by the women interviewed at home. CONCLUSION: The current maternal care system fails to effectively deal with obstetric complications. It needs to be better resourced, more easily available, cheaper and take into account the women's needs.

Is obesity associated with injuries among young people?

OBJECTIVES: To look at the relationship between obesity and trauma among young people in the Hainaut Province in Belgium. DESIGN: A cross-sectional study (questionnaire and physical examination) was conduced among a sample of 2363 children of 9- to 17-year-olds (n = 2363) in 1998. RESULTS: In the past 12 months prior to the survey, 37% of the sample had at least one injury requiring treatment (with or without hospitalization), and 5% had a severe injury (with at least one night at the hospital). More than 15% were classified to be obese according to the WHO definition. We observed a significantly higher frequency of injury in obese people, in boys, in subjects playing sport intensively, with members of a sports club and in those reporting more than one physical activity per week. In multivariate analysis for injury, gender, physical activity, playing sport in a club and obesity were significant. For severe injuries, only gender and physical activity remained significant in the multivariate analysis. CONCLUSION: Our analysis shows that childhood obesity and physical activity increase the occurrence of injuries. However, we did not observe an association between obesity and severe injuries. Obesity as a risk factor for the occurrence of injuries has to be confirmed by other studies, and the understanding of the mechanism for the observed association needs more investigation.

Intraembryonic, but not yolk sac hematopoietic precursors, isolated before circulation, provide long-term multilineage reconstitution.

The relative contribution of yolk sac and intraembryonic precursors to hematopoiesis has been a matter of long-standing controversy. As reconstitution activity has so far only been found in embryonic tissues after the onset of circulation, the origin of reconstituting cells could not be formally established. Here, we separated yolk sac and intraembryonic splanchnopleura prior to circulation and maintained the explants in organ culture before transfer. Precursors derived from the intraembryonic site generated multilineage hematopoietic progeny in adult mice for more than 6 months. Yolk sac cells only provided myeloid short-term reconstitution. The results reveal a differential hematopoietic capacity of precirculation embryonic tissues in vivo, and indicate that the only cells capable of adult long-term hematopoiesis are of intraembryonic origin.

[Microglia: origin and development]. / Microglie: origine et développement.

As suggested by Del Rio Ortega a long time ago, it is now widely accepted that microglia are the resident macrophages of the central nervous system. Microglia represent about 10% of the adult brain cell population. We have previously shown that the late embryonic and adult mouse brain contain potential microglial progenitors. We report here that microglial progenitors can be detected in neural folds from embryonic day 8. They originate from the yolk sac in which macrophage progenitors are found from embryonic day 7. We also report that the bulk of microglial cells (about 95%) appear during post-natal development. A major finding is that microglia arise by an intense in situ proliferation comparable to that of neural cells. Taken together, these results show that adult mouse microglia originate from cells migrating from the yolk sac and whose progeny actively proliferates in the brain during development.

Barriers to prenatal care in Europe.

BACKGROUND: In Europe, it is sometimes assumed that few barriers to prenatal care exist because extensive programs of health insurance and initiatives to promote participation in prenatal care have been established for many decades. METHODS: A case-control study was performed in ten European countries (Austria, Denmark, Germany, Greece, Hungary, Ireland, Italy, Portugal, Spain, and Sweden). Postpartum interviews were conducted between 1995 and 1996. A total of 1283 women with inadequate prenatal care (i.e., with 0, 1, or 2 prenatal care visits or a first prenatal care visit after 15 completed weeks of pregnancy) and 1280 controls with adequate prenatal care were included in the analysis combining data from the ten countries. RESULTS: Based on combined data of the ten countries, lack of health insurance was found to be an important risk factor for inadequate prenatal care (crude odds ratio [OR] at 95% confidence interval [CI]: 30.1 [20.1-47.1]). Women with inadequate prenatal care were more likely to be aged < 20 years (16.4% vs 4.8%) and with higher parity (number of children previously borne) than controls. They were more likely to be foreign nationals, unmarried, and with an unplanned pregnancy. Women with inadequate care were also more likely to have less education and no regular income. They had more difficulties dealing with health services organization and child care. Cultural and financial barriers were present, but after adjusting for confounders by logistic regression, perceived financial difficulty was not a significant factor for inadequate prenatal care (adjusted OR [95% CI]: 0.7 [0.4-1.3]). CONCLUSIONS: Personal, socioeconomic, organizational, and cultural barriers to prenatal care exist in Europe.

Pluripotent hematopoietic stem cell development during embryogenesis.

Significant progress has been made towards a better understanding of the establishment of hematopoiesis in the embryo. Hematopoietic precursors have been shown to arise independently in the yolk sac and in the intra-embryonic mesoderm. From the combined analysis of differentiation potentials, expression patterns and mutant phenotypes, a picture has emerged: definitive hematopoietic precursors are transiently generated in a specific environment close to the endothelium of the main arteries.

Blood pressure measurement in epidemiological investigations in teenagers.

BACKGROUND: The use of sphygmomanometers may lead to problems in investigations on health of young people. The purpose of this paper is to present the validation of the blood pressure (BP) collected during the survey 'Youth Heart Health' in Hainaut by using second sample of young people in Hainaut for which BP was measured by a manual taking of tension and by an electronic device. METHODS: Validation was done with a control sample of 343 young with five successive BP measures: twice with the mercury sphygmomanometer and three with DXL. We compared the manual and the electronic measures in order to study the correlation between the two methods. The control sample was used in order to compare the BP measurements with the results of the survey on the health of young people in Hainaut. RESULTS: The differences between manual systolic BP and Dinamap measures are significant (differences in averages 3.6 mmHg; d.s. 7.8; 95% CI: 2.8-4.4 mmHg; p < 0.001) and the regression coefficient is -0.015. Diastolic BP is significantly higher with the manual method than with Dinamap (differences in means: 8.2 mmHg; d.s. 7.0; 95% CI: 7.4-8.9 mmHg; p < 0.001) and the coefficient of regression is 0.096. We observe a difference in BP between the general survey and the control group (10.3 mmHg for systolic manual control and of 10.9 mmHg for systolic electronic control; 3.3 mmHg for diastolic manual control and of 11.5 mmHg for diastolic electronic control). CONCLUSIONS: The values of BP of the 'Youth Heart Health' are significantly higher. These observations indicate the difficulties in the choice of the tool for measurements of BP in epidemiological investigations in the teenagers. In order to decrease skews of observations in the measurement of BP, it is recommended to use a valid electronic instrument. Dinamap XL is an instrument of choice in such studies of young people. Environmental and organisational factors may also explain the observed difference, which means that survey's protocols should address this issue carefully.