Health effects of dental amalgam exposure: a retrospective cohort study

BACKGROUND: Whether dental amalgam fillings (containing mercury) are hazardous is a long-standing issue, with few epidemiological investigations. Allegations have particularly involved nervous system disorders, such as multiple sclerosis, Alzheimer's disease, and chronic fatigue syndrome. This retrospective cohort study, the largest of its kind, contained people in the New Zealand Defence Force (NZDF) between 1977 and 1997. The NZDF has its own dental service, providing all personnel with regular and consistent treatment. Comprehensive treatment records are maintained and archived. METHODS: Yearly dental treatment histories, including amalgam filling placements, were compiled from individual records. To minimize amalgam exposure misclassification the cohort was restricted to people who, at NZDF entry, were aged <26 years and had all their posterior teeth. The cohort was linked with morbidity records. Data were analysed with a proportional hazards model, using a time-varying exposure unit of 100 amalgam surface-years. RESULTS: The final cohort contained 20 000 people, 84% males. Associations with medical diagnostic categories, particularly disorders of the nervous system and kidney, were examined. Of conditions allegedly associated with amalgam, multiple sclerosis had an adjusted hazard ratio (HR) of 1.24 (95% CI: 0.99, 1.53, P = 0.06), but there was no association with chronic fatigue syndrome (HR = 0.98, 95% CI: 0.94, 1.03), or kidney diseases. There were insufficient cases for investigation of Alzheimer's or Parkinson's diseases. CONCLUSIONS: Results were generally reassuring, and provide only limited evidence of an association between amalgam and disease. Further follow-up of the cohort will permit investigation of diseases more common in the elderly.     

幼儿口腔健康影响程度量表初步研究

为研制合乎中国国情的<3～6岁儿童口腔健康影响量表>(ECOHIS中文版),评估口腔疾病对3～6岁儿童的日常生活行为及其家庭的影响,采用议题小组和核心小组的程序化决策方式确定初选项目;采取随机抽样方法抽取患者进行调查,应用变异系数法、因子分析法和相关分析方法对调查结果进行统计学分析,对初选条目进行完善.在此基础上研制出ECOHIS中文版, 包含躯体功能、心理功能、社会功能、对家庭的影响4个领域,共计23个条目.经现场验证,ECOHIS中文版具有较好的内容效度.     

幼儿口腔健康影响程度量表初步研究

为研制合乎中国国情的《3~6岁儿童口腔健康影响量表》(ECOH IS中文版),评估口腔疾病对3~6岁儿童的日常生活行为及其家庭的影响,采用议题小组和核心小组的程序化决策方式确定初选项目;采取随机抽样方法抽取患者进行调查,应用变异系数法、因子分析法和相关分析方法对调查结果进行统计学分析,对初选条目进行完善。在此基础上研制出ECOH IS中文版,包含躯体功能、心理功能、社会功能、对家庭的影响4个领域,共计23个条目。经现场验证,ECOH IS中文版具有较好的内容效度。     

The Impact of Oral Health on the Academic Performance of Disadvantaged Children

Objectives. We measured the impact of dental diseases on the academic performance of disadvantaged children by sociodemographic characteristics and access to care determinantsMethods. We performed clinical dental examinations on 1495 disadvantaged elementary and high school students from Los Angeles County public schools. We matched data with academic achievement and attendance data provided by the school district and linked these to the child’s social determinants of oral health and the impact of oral health on the child’s school and the parents’ school or work absences.Results. Students with toothaches were almost 4 times more likely to have a low grade point average. About 11% of students with inaccessible needed dental care missed school compared with 4% of those with access. Per 100 elementary and high school–aged children, 58 and 80 school hours, respectively, are missed annually. Parents averaged 2.5 absent days from work or school per year because of their children’s dental problems.Conclusions. Oral health affects students’ academic performance. Studies are needed that unbundle the clinical, socioeconomic, and cultural challenges associated with this epidemic of dental disease in children.Poor oral health affects systemic health with consequences that can seriously compromise quality of life and life expectancy. Oral diseases can lead to systemic diseases, emergency hospital visits, hospital stays, medications, even death. Moreover, oral disease can increase personal, societal, and financial burdens and contribute to rising health care costs in general.1Anecdotally, we know that there is an epidemic of dental diseases among disadvantaged children in Los Angeles County, as is consistently observed by health professionals and community stakeholders. To quantify this observation, we established a campus–community project with the goals of measuring this epidemic and its impact and designing appropriate intervention programs to ultimately reduce the burden of poor oral health among these children. Previously, we documented that the overall prevalence of dental caries in this population of disadvantaged children was 73% and that no important racial/ethnic differences were found between Blacks, Asians, White, and non-White or “other” Hispanics.2 One aspect of this project, which we have reported in this article, is to measure the impact of dental diseases on the academic performance of these disadvantaged children by their sociodemographic characteristics and access to care determinants.It has been suggested that objective measures of oral health should be linked to measures of social outcome to place dental conditions within a broader context that is relevant to policymakers.3 Based on the National Health Interview Survey of 1989, it has been estimated that 51 million school hours are lost yearly because of dental disease based on a 15-day recollection.4 This result has been widely cited. A Google search provided more than 57 000 hits when queried for “dental” + “51 million school hours.” According to the Thomson Scientific’s Institute for Scientific Information web of knowledge, this resource has been cited in the scientific literature 55 times. More recently, the California Health Interview Survey asked about the number of school days missed in the past year because of dental problems; the question was asked only in the survey of 2007.5 No other literature sources provide definitive estimates of the number of school hours missed because of dental problems besides that reported by Gift et al.,4 nor is there any estimation of the impact of oral health on the students’ academic achievement. Furthermore, it should be noted that the means and SDs reported by Gift et al. were acknowledged as being inaccurate, and no corrected estimates were subsequently published.6 We have provided an updated estimate of the impact of dental problems on disadvantaged children missing school and parents missing school or work based on their 1-year recall. Also, we explored the relationship of oral health with academic achievement and attendance by school level, gender, and race/ethnicity. We will report other aspects of the project elsewhere.2     

Impact of Medicaid Policy on the Oral Health of Publicly Insured Children

Objective Fluoride varnish (FV) applications among non-dentist primary care providers has increased due to state Medicaid policies. In this study we examine the impact of FV policies on the oral health of publicly insured children aged 2–6 years old. Methods Using three waves of the National Survey of Children’s Health (2003, 2007, 2011/12), we used a logistic regression model with state and year fixed effects, adjusting for relevant child characteristics, to examine the association between years since a state implemented a FV policy and the odds of a publicly insured child having very good or excellent teeth. We compared children with public insurance in states with FV policies to children with public insurance in states without FV policies, controlling for the same difference among children with private insurance who were unlikely to be affected by Medicaid FV policies. Results Among 68,890 children aged 2–6 years, 38% had public insurance. Compared to privately insured children, publicly insured children had significantly lower odds of having very good or excellent teeth [odds ratio (OR) 0.70, 95% CI 0.62–0.81]. Publicly insured children in states with FV policies implemented for four or more years had significantly greater odds of having very good or excellent teeth (OR 1.28, 95% CI 1.03–1.60) compared to publicly insured children in states without FV policies. Conclusions for Practice State policies supporting non-dental primary care providers application of FV were associated with improvements in oral health for young children with public insurance.

     

Bias in estimating the causal hazard ratio when using two‐stage instrumental variable methods

Two‐stage instrumental variable methods are commonly used to estimate the causal effects of treatments on survival in the presence of measured and unmeasured confounding. Two‐stage residual inclusion (2SRI) has been the method of choice over two‐stage predictor substitution (2SPS) in clinical studies. We directly compare the bias in the causal hazard ratio estimated by these two methods. Under a principal stratification framework, we derive a closed‐form solution for asymptotic bias of the causal hazard ratio among compliers for both the 2SPS and 2SRI methods when survival time follows the Weibull distribution with random censoring. When there is no unmeasured confounding and no always takers, our analytic results show that 2SRI is generally asymptotically unbiased, but 2SPS is not. However, when there is substantial unmeasured confounding, 2SPS performs better than 2SRI with respect to bias under certain scenarios. We use extensive simulation studies to confirm the analytic results from our closed‐form solutions. We apply these two methods to prostate cancer treatment data from Surveillance, Epidemiology and End Results‐Medicare and compare these 2SRI and 2SPS estimates with results from two published randomized trials. Copyright © 2015 John Wiley & Sons, Ltd.     

Psychometric Characteristics of the Croatian and the Serbian Versions of the Oral Health Impact Profile for Edentulous Subjects,with a Pilot Study on the Dimensionality

IntroductionThe aim was to adapt the Croatian and the Serbian versions of the Oral Health Impact Profile for the edentulous population (OHIP-EDENT-CRO and OHIP-EDENT-SRB).MethodsThe translation and cross-cultural adaptation were carried out in accordance with accepted international standards. A total of 95 and 177 removable denture wearers were recruited in Croatia and Serbia respectively. The reliability was evaluated by calculating Cronbach’s alpha coefficient and by test-retest (30 participants in each country). The concurrent validity was determined by calculating the Spearman’s rank coefficient between the OHIP-EDENT summary scores and one question related to removable denture satisfaction. Construct validity was determined by exploratory factor analysis (EFA). Responsiveness was determined by comparison of the OHIP-EDENT summary scores before and after dental implant placement to support mandibular overdentures (23 patients in Croatia, 21 in Serbia).ResultsCronbach’s alpha coefficient was 0.92 in Croatia and 0.87 in Serbia. The intraclass correlation coefficient was 0.98 in Croatia and 0.94 in Serbia. In Croatia the Spearman’s correlation coefficient was -0.71 (p<0.001) and in Serbia -0.74 (p<0.001). Both confirmed concurrent validity. Construct validity was tested by EFA, which extracted four factors in each country, accounting for 66.59% of the variance in Croatia and 59.33% in Serbia. Responsiveness was confirmed in both countries by a significant OHIP-EDENT summary score reduction and a high standardised effect size (3.9 in Croatia, 1.53 in Serbia).ConclusionThe results prove that both instruments, the OHIP-EDENT-CRO and the OHIP-EDENT-SRB, have very good psychometric properties for assessing OHRQoL in the edentulous population.     

Semantic equivalence of the Brazilian version of the Early Childhood Oral Health Impact Scale

The North American instrument Early Childhood Oral Health Impact Scale (ECOHIS) was created to assess the oral health-related quality of life of preschool children and their families. Its use in Brazil requires prior cultural adaptation, and semantic equivalence is one step in this process. The objective of this study was to evaluate the semantic equivalence between the ECOHIS and its Brazilian version. The methodology included six steps: translation of the ECOHIS into Portuguese, done by two translators; a pre-test, in which the two translations were tested in a group of 20 parents/guardians of children 2-5 years of age; unification of the two versions; two back-translations done independently by two translators; review of the translations and back-translations; and production of a final version of the questionnaire. The two translated versions were very similar, and after completion of all steps a final version of the ECOHIS was obtained. The use of translations and back-translations carefully evaluated by experts and incorporating suggestions from the target population allowed the development of a Brazilian version of the ECOHIS that is semantically equivalent to the original instrument.     

Measurement of health-related quality of life of patients receiving conservative treatment for limb lymphoedema using the Nottingham Health Profile

There is increasing interest in the health-related quality of life (HRQOL) of patients with chronic oedema. Studies in this area have tended to be exploratory and little work has examined the potential for HRQOL as a treatment outcome indicator in this context. This study aimed to ascertain whether or not conservative treatment for lymphoedema results in a measurable change in HRQOL, using the Nottingham Health Profile Part 1 (NHP-1) as the study instrument. Thirty-four patients participated. The patients received a range of conservative treatments. The participants completed the NHP-1 prior to treatment and 4 weeks after completion of the initial treatment phase. The overall post-treatment NHP-1 scores were significantly lower than the overall pre-treatment scores (z=3.1 and p<0.01), indicating an improvement in the HRQOL. The greatest change in a single dimension was in physical mobility (z=2.3 and p<0.05). The change in limb volume was not associated with a change in any NHP-1 subscale. A significant correlation was found between an improvement in skin condition and an improvement in scores on the pain subscale (r=0.53 and P<0.01). It is concluded that the NHP-1 was useful in the assessment of the physical domains of HRQOL in this context, but was less useful with regard to psychological and emotional domains.     

The Impact of Functional Health Literacy and Acculturation on the Oral Health Status of Somali Refugees Living in Massachusetts

Objectives. We assessed the impact of health literacy and acculturation on oral health status of Somali refugees in Massachusetts.Methods. Between December 2009 and June 2011, we surveyed 439 adult Somalis who had lived in the United States 10 years or less. Assessments included oral examinations with decayed, missing, and filled teeth (DMFT) counts and measurement of spoken English and health literacy. We tested associations with generalized linear regression models.Results. Participants had means of 1.4 decayed, 2.8 missing, and 1.3 filled teeth. Among participants who had been in the United States 0 to 4 years, lower health literacy scores correlated with lower DMFT (rate ratio [RR] = 0.78; P = .016). Among participants who had been in the country 5 to 10 years, lower literacy scores correlated with higher DMFT (RR = 1.37; P = .012). Literacy was not significantly associated with decayed teeth. Lower literacy scores correlated marginally with lower risk of periodontal disease (odds ratio = 0.22; P = .047).Conclusions. Worsening oral health of Somali refugees over time may be linked to less access to preventive care and less utilization of beneficial oral hygiene practices.Among refugees newly arrived in Massachusetts, oral abnormalities are the most common health problem in children1 and the second most common problem in adults. One major determinant of oral health disparities is access to preventive and restorative dental care.2 Other determinants include oral hygiene practices and diet.2 Linguistic and cultural factors may play important roles in determining access to oral health services as well as personal oral hygiene practices, and limited literacy skills have been hypothesized as a likely barrier to better oral health outcomes.3Health literacy, reflecting an individual’s capacity to obtain, process, and understand basic health information and services, affects a variety of determinants of oral health and is thought to play a pervasive role in all aspects of health care and oral health status.3,4 Inadequate health literacy has been associated with a long and growing list of adverse health outcomes.5 Inadequate literacy has been associated with limited access and utilization of care,6,7 poor clinical outcomes,8 hospitalization,9 and mortality.10 However, the relationship between health literacy and oral health has never been studied in a refugee population.Somalis compose one of the largest refugee populations to have entered the United States in recent years. As a result of civil war over the past 20 years, many Somalis have lived in refugee camps for long periods. More recently arrived Somalis have very low English literacy.11 Somalis are almost all practicing Muslims and have relative homogeneity of language, culture, and religion.12,13 In the United States, Somali refugees have also tended to cluster geographically through a process known as secondary migration to create cohesive communities. Past research indicated a strong role for such social structures as moderators of health literacy and its impact on health status.14 A refugee with low literacy may be able to effectively access care with the help of the community network. Thus, health literacy may function differently in the context of the Somali community, with its strong social support network. The degree to which an individual identifies with the traditional community and social structure or that of the dominant, host community varies and may affect how an individual negotiates competing priorities related to personal oral hygiene, diet, and access to dental care.Behavioral acculturation is a measure of such factors as with whom people spend time, the types of media they are exposed to, the language in which they feel most comfortable conversing and reading, and with whom they identify. The effects of acculturation on oral health have been studied in Haitian immigrants in the United States who had a low baseline rate of caries. Acculturation was found to be associated with lower rates of development of caries.15 In Australia, a study of Vietnamese refugees revealed associations between acculturation and dental health status.16 The Vietnamese also had very good oral health status, and those with extensive acculturation had even better oral health status. This finding suggested that more acculturation led to protective practices and care that added to those of the refugees’ traditional culture.However, the findings documented a nonlinear relationship in which refugees with moderate levels of acculturation had worse oral health status. The researchers hypothesized that the cultural marginality model, previously applied to oral health research,17,18 offered an explanation: refugees with moderate levels of acculturation were alienated from their traditional culture without adequate integration into the dominant culture. Thus, moderately acculturated refugees might adopt behaviors deleterious to oral health, such as Western dietary habits, without adopting preventive aspects of Western oral hygiene and related behaviors.16 By contrast, individuals with a low level of acculturation may have continued beneficial traditional practices and not adopted a cariogenic Western diet. In the Somali community, one such practice might be use of a stick brush (miswak or aday). Studies have found stick brushes to be effective in removing plaque.11,19 These brushes also have an inhibitory effect on oral cariogenic streptococci20,21 and periodontal pathogens.21In light of the importance of health literacy to health in the general population, we sought to determine the relationship of health literacy (assessed in English) with oral health clinical outcomes of Somali refugees in Massachusetts. We hypothesized that after control for acculturation, participants with high health literacy would be more likely than others to have (1) less lifetime history of decay, untreated dental decay, and periodontal disease; (2) a higher rate of traditional or Western personal hygiene practices and behaviors known to be associated with better oral health outcomes; and (3) more utilization of professional dental care for preventive services. We also assessed functional and mental health outcomes and a variety of social and cultural factors relevant to the effects of literacy, acculturation, oral health care, and personal hygiene practices on oral health status in the Somali community.     

某高校大学生参与式口腔健康教育效果评价

目的 评价参与式口腔健康教育对大学生牙周健康状况及相关知识、行为的影响,探索适合大学生人群的口腔健康教育模式.方法 采用分层、不等比随机抽样的方法,选取昆明理工大学40个宿舍(教育组、对照组各20个)共240名学生.教育组学生在专题小组访谈的基础上,进行小组讨论形式的参与式口腔健康教育,同时提供专为口腔健康教育设计的阅读材料,使用统一提供的牙膏、牙刷和手动牙线;对照组不进行任何干预措施.在健康教育后,比较2组学生牙周健康状况、口腔卫生知识和行为的改善情况.结果 3个月后,教育组学生的软垢指数(0.89)、牙石指数(0.23)、牙龈指数(0.21)明显低于对照组(1.56,0.73,1.17)(P值均<0.05);教育组学生每天刷牙的次数以及每次刷牙的时间均优于对照组学生(P值均<0.01);刷牙方法、牙周疾病等口腔保健知识知晓率教育组优于对照组,差异均有统计学意义.结论 参与式口腔健康教育方法能明显改善大学生的口腔卫生状况,提高参与者的口腔卫生知识和行为.     

Moving towards best practice when using inverse probability of treatment weighting (IPTW) using the propensity score to estimate causal treatment effects in observational studies

The propensity score is defined as a subject's probability of treatment selection, conditional on observed baseline covariates. Weighting subjects by the inverse probability of treatment received creates a synthetic sample in which treatment assignment is independent of measured baseline covariates. Inverse probability of treatment weighting (IPTW) using the propensity score allows one to obtain unbiased estimates of average treatment effects. However, these estimates are only valid if there are no residual systematic differences in observed baseline characteristics between treated and control subjects in the sample weighted by the estimated inverse probability of treatment. We report on a systematic literature review, in which we found that the use of IPTW has increased rapidly in recent years, but that in the most recent year, a majority of studies did not formally examine whether weighting balanced measured covariates between treatment groups. We then proceed to describe a suite of quantitative and qualitative methods that allow one to assess whether measured baseline covariates are balanced between treatment groups in the weighted sample. The quantitative methods use the weighted standardized difference to compare means, prevalences, higher‐order moments, and interactions. The qualitative methods employ graphical methods to compare the distribution of continuous baseline covariates between treated and control subjects in the weighted sample. Finally, we illustrate the application of these methods in an empirical case study. We propose a formal set of balance diagnostics that contribute towards an evolving concept of ‘best practice’ when using IPTW to estimate causal treatment effects using observational data. © 2015 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd.     

Impact of resistance to anti-tuberculosis drugs on treatment outcome using World Health Organization standard regimens

We compared treatment outcome in 410 patients with drug-susceptible tuberculosis (DS-TB) and 150 patients with drug-resistant tuberculosis (DR-TB) among 560 adult patients (> or = 15 years old) notified with smear-positive pulmonary tuberculosis between July 1997 and June 1998 in the West Province of Cameroon and treated with World Health Organization (WHO) standard regimens under field conditions. Information on treatment outcome was collected for all smear-positive TB patients having a positive culture with drug susceptibility tests performed for isoniazid, rifampicin, ethambutol and streptomycin. Treatment outcome was recorded as cured, completed treatment, failed, defaulted, died or transferred out, 332 of the 410 patients (81%) with DS-TB were cured, compared to 109/150 (72.7%) patients with DR-TB (odds ratio [OR] = 0.62, 95% confidence interval [CI] 0.40-0.99). Seven patients (1.7%) failed treatment in the DS-TB group vs. 9 (6.0%) in the DR-TB group (OR = 3.67, 95% CI 1.23-11.18). No significant difference was found in rates of death, default or transfer. Sputum smear conversion at the end of the intensive treatment phase was observed in 78.8% of the cases, drug resistance having no effect on the conversion rate. After adjusting for age, sex and resistance, the death rate was higher in patients also infected with human immunodeficiency virus (HIV). In TB cases with multidrug resistance, standard regimens result in unacceptably high failure rates (26.1%). For all other drug-resistant forms of TB, rifampicin-based short-course chemotherapy gave satisfactory results. The death toll in the West Province seems due to HIV co-infection rather than to TB alone. To prevent development of drug-resistance, the proportion of defaulters must be decreased and prevention and control strategies endorsed by the WHO and the International Union Against Tuberculosis and Lung Disease must be implemented nation-wide.     

Validations of the Brazilian version of the Early Childhood Oral Health Impact Scale (ECOHIS)

This study aimed to evaluate the psychometric properties of the Brazilian version of the Early Childhood Oral Health Impact Scale (ECOHIS). A total of 247 children aged 2 to 5 years and their parents/guardians participated in this study. A clinical oral examination was performed and the parents/guardians completed the ECOHIS questionnaire. Within a period of four-weeks, 20% of the participants repeated the ECOHIS questionnaire. Construct validity was determined using Spearman's rank correlation. Discriminant validity, internal consistency and test-retest reliability were also evaluated. The children were divided into 2 groups: group 1 (with dental caries) and group 2 (caries-free). Children with caries showed higher mean ECOHIS scores than the caries-free children. The child impact section (p < 0.01), family impact section (p < 0.01) and total ECOHIS scores (p < 0.01) were significantly correlated with tooth decay. Cronbach's alpha coefficients demonstrated satisfactory internal consistency. The Brazilian version of the ECOHIS is a valid instrument for assessing oral health-related quality of life in preschool children with Brazilian Portuguese-speaking primary caregivers.