Study of the Unidimensionality of the Subjective Measurement Scale of Schizophrenia Coping Oral Health Profile and Index: SCOOHPI.

BACKGROUND: The Schizophrenia Coping Oral Health Profile and Index (SCOOHPI) scale studies the coping strategies of schizophrenic patients with regard to oral health. The structural validity of this scale is studied has been studied using factor analyses. In this article, we study the unidimensionality of the SCOOHPI scale to use it as an index. METHODS: We studied the internal consistency of the items of the SCOOHPI scale. Then, we studied the construct validity. The unidimensionality of the SCOOHPI scale was studied by the partial credit model. RESULTS: The data used in this study come from five hospitals, and the total number of individuals participating in this study is 96, of which 72% are men and 59% are smokers. The SCOOHPI scale has good internal consistency (α = 0.84). The validity of divergence was checked by the absence of correlation between the SCOOHPI scale and the GOHAI (General Oral Health Assessment Index) scale. The unidimensionality of the SCOOHPI scale with data smoothing was demonstrated by the partial credit model. CONCLUSION: In this study, we completed the study of the psychometric validation of the SCOOHPI. The SCOOHPI scale can then contribute to improving evaluation of the coping strategies of schizophrenic patients with regard to oral health.

Genetic diversity of Mycobacterium tuberculosis strains isolated in Algeria: Results of spoligotyping.

OBJECTIVE/BACKGROUND: Molecular typing tools, including spoligotyping, are currently widely used in the monitoring and study of the dynamics of tuberculosis epidemics. METHODS: A study of the molecular profile of a sample of 129 Myobacterium tuberculosis strains isolated during 2011 was carried out in the National Reference Laboratory for Tuberculosis and Mycobacteria at the Pasteur Institute of Algeria. This sample was selected at random from a set of 350 strains isolated from tuberculosis patients from central and eastern areas of the country. RESULTS: Genotypic analysis helped to clarify the frequencies of the different genotypes in the current study population: H family, 29%; LAM family, 26%; T family, 25%; S family, 5%, and other genomic families, including orphan strains, 15%. CONCLUSION: The study of strains isolated between January and December 2011 has allowed insight into the frequency of different genomic families and the importance of existing clusters in the population of central and eastern Algeria.

Statistical challenges of quality of life and cancer: new avenues for future research.

Statistical modeling conference on the quality of life measurements of the French National Platform of Quality of Life and Cancer Faculty of Science in Luminy, Marseille, France, 12-13 September 2013 The French National Platform of Quality of Life and Cancer and the statistical team of the Mathematical Institute of Luminy undertook a successful first conference addressing the statistical challenges of measuring the quality of life in the field of oncology. More than 15 presentations were made over a 2-day period by the Faculty of Sciences in Luminy. The conference managed to assemble participants from different disciplines, such as mathematics and statistics, public health, epidemiology and psychology, to debate the key statistical and methodological issues of quality of life measurement and analysis. Three main topics were covered in this conference: the treatment of missing data, the development of item banking and computerised adaptive testing and the detection/understanding of response shift.

Using extended Rasch models to assess validity of diagnostic tests in the presence of a reference standard.

We show that extended Rasch models, built to deal with continuous latent variables, may be useful for assessing validity of medical diagnostic tests in the presence of a reference standard, particularly for chronic diseases. We derive estimates for sensitivity and specificity under the Rasch model assumptions. Our estimations can be computed conditionally on the level of potential confounding covariates, making use of a variety of extended Rasch models, namely log-linear Rasch models, to examine the association between covariates and both disease intensity and response to the tests. Also, another variety of extended Rasch models, partial credit models, can determine appropriate thresholds for quantitative diagnostic tests. As an example, we study the validity of some diagnostic tests of heart failure.

A new air quality perception scale for global assessment of air pollution health effects.

Despite improvements in air quality in developed countries, air pollution remains a major public health issue. To fully assess the health impact, we must consider that air pollution exposure has both physical and psychological effects; this latter dimension, less documented, is more difficult to measure and subjective indicators constitute an appropriate alternative. In this context, this work presents the methodological development of a new scale to measure the perception of air quality, useful as an exposure or risk appraisal metric in public health contexts. On the basis of the responses from 2,522 subjects in eight French cities, psychometric methods are used to construct the scale from 22 items that assess risk perception (anxiety about health and quality of life) and the extent to which air pollution is a nuisance (sensorial perception and symptoms). The scale is robust, reproducible, and discriminates between subpopulations more susceptible to poor air pollution perception. The individual risk factors of poor air pollution perception are coherent with those findings in the risk perception literature. Perception of air pollution by the general public is a key issue in the development of comprehensive risk assessment studies as well as in air pollution risk management and policy. This study offers a useful new tool to measure such efforts and to help set priorities for air quality improvements in combination with air quality measurements.

Metric properties of the MacDQoL, individualized macular-disease-specific quality of life instrument, and newly identified subscales in French, German, Italian, and American populations.

OBJECTIVES: The aims of this analysis were to confirm the UK results in other countries and to explore the possibility of subscales of the 25-Item Macular disease Dependent Quality of Life (MacDQoL) questionnaire. METHODS: Two clinical studies were pooled. Principal components analyses (Varimax) were conducted on baseline data from each country and from all combined. Factorial structures were compared between countries, and Cronbach alpha values were used to identify item clusters. Four groups of patients were created according to visual acuity (VA) in the best eye (BE < 10/20; BE ≥ 10/20) and worst eye (WE < 10/100; WE ≥ 10/100). These groups were used to investigate (analysis of variance) the sensitivity of MacDQoL to VA impairment and to compare it with the NEI-VFQ-25 generic visual function questionnaire. RESULTS: A total of 797 patients (mean age 76.8 years; 55.8% women) had wet age-related macular degeneration (AMD). Strong correlations between the MacDQoL items (r > 0.48) and factor loadings > 0.49 on a forced one-factor analysis supported the use of an average weighted impact score. Four constructs (Cronbach alpha > 0.8) were derived, represented by the labels: Essential tasks, Family/social life, Activities/capabilities, and Embarrassment. The structure did not differ among the four countries involved, except one item (Finance), which has been excluded. Patients with BE VA <10/20 and WE VA <10/100 produced significantly worse overall scores than those with BE VA >10/20 and WE VA >10/100 (MacDQoL P < 0.0001; NEI-VFQ-25 P < 0.0001). CONCLUSIONS: The analysis confirmed the metric properties of the MacDQoL. The MacDQoL offers a broad individualized measure of the impact of MD on quality of life.

Factors associated with psychological and behavioral functioning in people with type 2 diabetes living in France.

BACKGROUND: To identify demographic and clinical factors associated with psychological and behavioral functioning (PBF) in people with type 2 diabetes living in France. METHODS: In March 2002, approximately 10,000 adults, who had been reimbursed for at least one hypoglycemic treatment or insulin dose during the last quarter of 2001, received a questionnaire about their health status and PBF (3,646 responders). For this analysis, the 3,090 persons with type 2 diabetes, aged 18-85 years old were selected.PBF was measured with the adapted version of the Diabetes Health Profile for people with type 2 diabetes. This permitted the calculation of three functional scores - psychological distress (PD), barriers to activity (BA), and disinhibited eating (DE) - from 0 (worst) to 100 (best). RESULTS: Major negative associations were observed with PBF for microvascular complications (a difference of 6.7 in the BA score between persons with and without microvascular complications) and severe hypoglycemia (difference of 7.9 in the BA score), insulin treatment (-8.5 & -9.5 in the PD & BA scores respectively, as compared to treatment with oral hypoglycemic agents), non-adherence to treatment (-12.3 in the DE score for persons forgetting their weekly treatment), increasing weight (-8.5 & -9.7 in the PD & DE scores respectively, as compared to stable weight), at least one psychiatrist visit in 2001 (-8.9 in the DE score), and universal medical insurance coverage (-7.9 in the PD score) (due to low income). CONCLUSION: Prevention and management of microvascular complications or adherence to treatment (modifiable factors) could be essential to preserving or improving PBF among people with type 2 diabetes. A specific approach to type 2 diabetes management may be required in groups with a low socioeconomic profile (particularly people with universal medical insurance coverage), or other non modifiable factors.

Winter air pollution and infant bronchiolitis in Paris.

Respiratory syncytial virus (RSV) is one of the most common respiratory pathogens in infants and young children. It is not known why some previously healthy infants, when in contact with RSV, develop bronchiolitis whereas others have only mild symptoms. Our study aimed to evaluate the possible association between emergency hospital visits for bronchiolitis and air pollution in the Paris region during four winter seasons. We included children under the age of 3 years who attended emergency room services for bronchiolitis (following standardized definition) during the period 1997-2001. Two series of data from 34 hospitals, the daily number of emergency hospital consultations (n=50857) and the daily number of hospitalizations (n=16588) for bronchiolitis, were analyzed using alternative statistical methods; these were the generalized additive model (GAM) and case-crossover models. After adjustments for public holidays, holidays and meteorological variables the case-crossover model showed that PM10, BS, SO2 and NO2 were positively associated with both consultations and hospitalizations. GAM models, adjusting for long-term trend, seasonality, holiday, public holiday, weekday and meteorological variables, gave similar results for SO2 and PM10. This study shows that air pollution may act as a trigger for the occurrence of acute severe bronchiolitis cases.

Sequential analysis of latent variables using mixed-effect latent variable models: Impact of non-informative and informative missing data.

Sequential methods allowing for early stopping of clinical trials are widely used in various therapeutic areas. These methods allow for the analysis of different types of endpoints (quantitative, qualitative, time to event) and often provide, in average, substantial reductions in sample size as compared with single-stage designs while maintaining pre-specified type I and II errors. Sequential methods are also used when analysing particular endpoints that cannot be directly measured, such as depression, quality of life, or cognitive functioning, which are often measured through questionnaires. These types of endpoints are usually referred to as latent variables and should be analysed with latent variable models. In addition, in most clinical trials studying such latent variables, incomplete data are not uncommon and the missing data process might also be non-ignorable. We investigated the impact of informative or non-informative missing data on the statistical properties of the double triangular test (DTT), combined with the mixed-effects Rasch model (MRM) for dichotomous responses or the traditional method based on observed patient's scores (S) to the questionnaire. The achieved type I errors for the DTT were usually close to the target value of 0.05 for both methods, but increased slightly for the MRM when informative missing data were present. The DTT was very close to the nominal power of 0.95 when the MRM was used, but substantially underpowered with the S method (reduction of about 23 per cent), irrespective of whether informative missing data were present or not. Moreover, the DTT using the MRM allowed for reaching a conclusion (under H(0) or H(1)) with fewer patients than the S method, the average sample number for the latter increasing importantly when the proportion of missing data increased. Incorporating MRM in sequential analysis of latent variables might provide a more powerful method than the traditional S method, even in the presence of non-informative or informative missing data.

Nonmedical economic consequences attributable to visual impairment: a nation-wide approach in France.

The nonmedical costs of visual impairment are crucial when allocating resources for prevention or treatment programs. Were analyzed the data from two representative nationwide French surveys aimed at documenting impairments that included 14,603 subjects living in institutions and 16,945 in the community. Three groups were identified: blind (light perception), low vision (loss of shape perception, LV), and controls. Item consumption was standardized on confounding factors using logistic regression. Costs attributable to visual impairment were estimated from control subjects. National nonmedical costs due to visual impairment were euro 9,806 million, arising mostly from LV (euro 8,735 million). The annual average cost/subject was euro 7,242 for LV and euro 15,679 for blindness. Loss of family income was euro 4,552 million, the burden on the caregiver euro 2,525 million, paid assistance euro 2,025 million, social allowances euro 0,942 million, and unmet needs euro 5,553 million. Resource allocation strategies aimed at controlling visual impairment should cover all relevant economic dimensions, including nonmedical items.

Prevalence of visual impairment in relation to the number of ophthalmologists in a given area: a nationwide approach.

BACKGROUND: Sociological and economic risk factors of visual impairment have never been described in France at a national level as the association between the number of ophthalmologists per inhabitant and visual impairment prevalence. METHODS: Two national surveys were pooled. First, 2075 institutions were selected at random from the French Health Ministry files. Second, a random, stratified sample of 356,208 citizens living in the community was selected. Blindness and low vision (LV) prevalence rates were estimated by age and gender. Geographical equities were estimated by logistic regression adjusted on age and occupational category. The association between ophthalmologist density and visual impairment prevalence rate was estimated per region. Interviews were completed with 14,603 (94.9%) of 15,403 randomly selected subjects in institutions, and 16,945 (77.8%) of 21,760 randomly selected subjects in the community. Three groups were defined from the interviews: low vision, blind, and control. RESULTS: Prevalence rates were LV 2.08% and blindness 0.12%. Both rates increased exponentially with age. No major difference was found with gender. Injury was the declared reason for both LV (12%) and blindness (12%). Large regional differences in prevalence persisted for LV after adjustment on age and occupation (ORs: 0.35 to 2.10), but not for blindness. Regions with ophthalmologists below the national per capita average were usually those with higher LV prevalence. CONCLUSION: An inverse correlation was found between ophthalmologist number and LV prevalence rates for subjects of similar age and socio-professional category. This denoted possible inequity in the provision of healthcare.

Scoring of visual field measured through Humphrey perimetry: principal component varimax rotation followed by validated cluster analysis.

PURPOSE: To extract unidimensional, well-separated latent scores that are anatomically and clinically valid from 52 standardized variables collected by Humphrey visual field (VF) perimetry (Carl Zeiss Meditec, Dublin, CA). METHODS: Visual field data of 437 patients were collected and classified by a glaucoma specialist into seven clinical groups: irregularities of VF (IVF), nasal step (NaS), arcuate scotoma (AC), paracentral scotoma (PCS), blind-spot enlargement (BSE), diffuse deficit (DD), and advanced deficit (AD). The number and content of constituent variable scores were identified by principal components analysis followed by Varimax Rotation and simple clustering, taking spatial distribution homogeneity and visual system anatomy into account. Unidimensionality was checked by a stepwise Cronbach alpha curve. Clinical predictability of the derived scores was checked by comparing clinical groups (ANOVA). RESULTS: Patients older than 60 years comprised 53.3% of the sample. The average mean deviation was -9.2 dB and pattern standard deviation was 6.5 dB. Six scores were identified: four peripheral scores (nasal superior, NS; nasal inferior, NI; temporal superior, TS; and temporal inferior, TI) and two paracentral scores (PCSs; superior, PCSS; and inferior, PCSI). Cronbach alpha was always >0.90. The six scores decreased sequentially from IVF to DD to AD. Scores of AC were lower in NS, NI, and TS; PCSS was less in PCS; BSE scores were less in TS and TI; NaS scores were less in NS and NI. CONCLUSIONS: Six well-separated, optimal scores were obtained from the Humphrey perimetry matrix. Internal reliability was good. It was possible to discriminate between clinical subgroups. Further analyses, based on longitudinal data, must be performed to confirm these findings.

Prevalence and burden of self-reported blindness, low vision, and visual impairment in the French community: a nationwide survey.

OBJECTIVE: To estimate the prevalence of self-reported visual impairment and its association with disabilities, handicaps, and socioeconomic consequences. METHODS: A national survey was conducted on a random stratified sample of 359 010 French citizens living in the community; 21 760 subjects were selected at random and 16 945 persons (78%) agreed to further questioning. Four thousand ninety-one randomly selected caregivers were interviewed. Four subgroups of subjects were defined (blind or light perception only, low vision or still have form perception, other visual problems, and no visual problems). These were compared after adjustment for age, comorbidity, and household size differences. RESULTS: The prevalence of blindness was 0.10% and of low vision, 1.94%. Subjects with blindness needed assistance with daily activities more often than subjects with no visual problems; they also needed more house modifications. Many subjects with blindness (46.8%) and subjects with low vision (29.0%) were registered for social allowances. Subjects with blindness had fewer paid activities (4.5%) than subjects with no visual problems (20.7%). Social allowances increased considerably (by 277) between those with low vision and those with blindness. Monthly household incomes were lower (P<.001) for subjects with low vision (1255) and blindness (1587) than for subjects with no visual problems (1851). MAIN OUTCOME MEASURES: Collected data included social demography, home description, household income, handicaps, disabilities, social allowances, and daily activities. CONCLUSION: The results demonstrate associations between self-reported visual impairment and daily living.

Prevalence and burden of self-reported blindness and low vision for individuals living in institutions: a nationwide survey.

BACKGROUND: The prevalence of self-reported low vision (LV) and blindness, and their associated disabilities, handicaps and socio-economic consequences for individuals living in institutions are poorly documented. METHODS: 2,075 institutions were selected at random and eight individuals were picked at random from the list of residents. Three groups of individuals were defined: blind, LV, and a control group (CG). These were compared after adjustment for age and co-morbidities. Of the 15,403 individuals, 14,603 interviews (94.9%) were completed. RESULTS: The prevalence of blindness was 1.6% and the LV 13.4%. Blind individuals needed assistance more often (OR: 2.65 to 11.35) than CG members while the assistance required by LV individuals was similar to that for the CG. Blind individuals required institution adaptation (building and furniture changes) more often than the CG. Blind (57.9%) and LV individuals (35.4%) were more often registered for social allowances. Monthly social allowances were EUR 86 higher for blind than LV individuals. Monthly family incomes were found to be similar between the three groups (from EUR 782 to 797). Social and demographic data, institution description, income, handicaps, disabilities, social allowances and details of daily activities were collected interviews. CONCLUSION: The results demonstrate the impact of self-reported blindness and LV on daily life for patients living in institutions.

Joint modeling of event time and nonignorable missing longitudinal data.

Survival studies usually collect on each participant, both duration until some terminal event and repeated measures of a time-dependent covariate. Such a covariate is referred to as an internal time-dependent covariate. Usually, some subjects drop out of the study before occurrence of the terminal event of interest. One may then wish to evaluate the relationship between time to dropout and the internal covariate. The Cox model is a standard framework for that purpose. Here, we address this problem in situations where the value of the covariate at dropout is unobserved. We suggest a joint model which combines a first-order Markov model for the longitudinally measured covariate with a time-dependent Cox model for the dropout process. We consider maximum likelihood estimation in this model and show how estimation can be carried out via the EM-algorithm. We state that the suggested joint model may have applications in the context of longitudinal data with nonignorable dropout. Indeed, it can be viewed as generalizing Diggle and Kenward's model (1994) to situations where dropout may occur at any point in time and may be censored. Hence we apply both models and compare their results on a data set concerning longitudinal measurements among patients in a cancer clinical trial.