[Evaluation of vision quality after laser vision correction in healthcare professionals]. / Évaluation de la qualité de vision après chirurgie réfractive au laser chez les professionnels de santé.

PURPOSE: Healthcare professionals require good quality of vision. The main objective of this study is to evaluate the satisfaction and vision quality after laser vision correction in healthcare professionals. METHODS: This is a monocentric retrospective study. An online 25-question survey was sent to ametropic physicians, surgeons and nurses who underwent corneal refractive surgery with laser-assisted in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) between July 2012 and February 2016. Questionnaire responses were recorded anonymously by the internet survey site. These patients' pre- and postoperative data were analyzed. RESULTS: In total, 2491 laser vision corrections were performed during this time frame. One hundred and fifty-eight patients were healthcare providers; 131 received the survey, and 111 responded. Ninety-nine were surgeons, 60 were medical physicians, and 32 were nurses. Ninety-one percent reported that they were satisfied with their postoperative vision quality, 63.9% even reported an improvement in their quality of vision compared with their corrected preoperative vision, 92.8% reported that they would have the procedure again, and 94.6% would recommend the procedure to a family member or a patient. Visual outcomes showed high levels of efficacy and predictability. CONCLUSION: While healthcare professionals require good quality of vision, those who had undergone laser vision correction reported the same satisfaction as the general population and would recommend the procedure to their family, friends and patients.

The cross-national epidemiology of panic disorder.

BACKGROUND: Epidemiological data on panic disorder from community studies from 10 countries around the world are presented to determine the consistency of findings across diverse cultures. METHOD: Data from independently conducted community surveys from 10 countries (the United States, Canada, Puerto Rico, France, West Germany, Italy, Lebanon, Taiwan, Korea, and New Zealand), using the Diagnostic Interview Schedule and DSM-III criteria and including over 40,000 subjects, were analyzed with appropriate standardization for age and sex differences among subjects from different countries. RESULTS: The lifetime prevalence rates for panic disorder ranged from 1.4 per 100 in Edmonton, Alberta, to 2.9 per 100 in Florence, Italy, with the exception of that in Taiwan, 0.4 per 100, where rates for most psychiatric disorders are low. Mean age at first onset was usually in early to middle adulthood. The rates were higher in female than male subjects in all countries. Panic disorder was associated with an increased risk of agoraphobia and major depression in all countries. CONCLUSIONS: Panic disorder is relatively consistent, with a few exceptions, in rates and patterns across different countries. It is unclear why the rates of panic and other psychiatric disorders are lower in Taiwan.

Marked 24-h rest/activity rhythms are associated with better quality of life, better response, and longer survival in patients with metastatic colorectal cancer and good performance status.

The rest/activity circadian cycle has been used as a reference for chemotherapy administration at specific times to improve tolerability and efficacy. Because cancer processes may be associated with alterations of circadian rhythms, the rest/activity cycle was monitored noninvasively to assess its relationship with tumor response, survival, and quality of life in 200 patients with metastatic colorectal cancer. Patients wore an actigraph, a wristwatch that records the number of accelerations per minute, for 3 days before receiving chronomodulated chemotherapy. The circadian rhythms in activity were estimated by two robust parameters: the autocorrelation coefficient at 24 h (r24), and the dichotomy index (I

An epidemiological reconsideration of the Geschwind-Galaburda theory of cerebral lateralization.

To contribute to the Geschwind-Galaburda theory of cerebral lateralization, we examined the relationship of left-handedness to allergic disorders and stuttering, using epidemiological data of two French samples, one of which (N = 9591) is representative of the French male population between 17 and 24 years of age. Results showed a higher frequency of stuttering but not of allergic disorders in left-handers. Extreme right-handedness was observed to be significantly associated with a lower frequency of allergic disorders; response bias might explain such a relationship. Findings were confirmed after allowing for potential confounding factors, such as age and education. In both samples, stuttering and allergic disorders were significantly related.

Age and cohort effects in adult handedness.

A systematic increase with age of the strong right-handers/mixed right-handers ratio, in normal adults, was found in Algeria, Greece, Italy, France and Spain. This age effect on adult handedness is not easily explained by variations in the social pressure against left-hand use, differential mortality, or information bias. There was no systematic decrease in the frequency of left-handedness with age. Left-hand writing among left-handers was common in the youngest age group and rare after 40 years of age.

Erythrocyte cation transport systems and plasma lipids in a general male population.

The relationships between five erythrocyte cation transport systems (Na(+)-K+ pump, Na(+)-K+ cotransport, Na(+)-Li+ countertransport and Na+ and K+ passive permeabilities) and plasma lipids (total plasma cholesterol, high-density lipoprotein cholesterol and triglycerides) were investigated in 129 male adult subjects with no known history of hypertension. Na+ and K+ erythrocyte contents were also considered for their possible relationships with plasma lipids. Na(+)-K+ cotransport and passive Na+ permeability were both significantly correlated with plasma triglycerides. Conversely, no significant correlation was found between erythrocyte cation transport systems or erythrocyte cation contents and total cholesterol. These findings suggest that plasma lipids can modulate erythrocyte ion transport activity in the general population.

Blood pressure and erythrocyte Na+ transport systems in a French urban male population.

This paper reports an investigation of blood pressure (taken as a continuous variable) as a function of: erythrocyte Na+ content; Na+,K+ pump; Na+,K+ cotransport and Na+,Li+ countertransport fluxes, and passive cation permeabilities in fresh erythrocytes from 129 French males who were living in an urban area and were not under treatment for any medical condition (after allowing for the effects of age, body mass index, alcohol and tobacco consumption). In contrast with previous findings in a North American population, we were unable to confirm that blood pressure was correlated with erythrocyte Na+ content and Na+,K+-AT-Pase activity. Conversely, the only transport parameter correlated (negatively) with blood pressure was outward Na+,K+ cotransport [r = -0.20, P less than 0.05 and r = -0.19, P less than 0.05, for systolic (SAP) and diastolic arterial pressure (DAP), respectively; n = 114]. When allowing for age, body mass index and alcohol consumption, the correlation coefficient between the Na+,K+ cotransport system and blood pressure increased from -0.20 to -0.28 (P less than 0.01) for SAP and from -0.19 to -0.28 (P less than 0.01) for DAP (n = 105). We conclude that the correlations between blood pressure and erythrocyte Na+ transport function could differ between North American and French (or Mediterranean) populations. In any case, a decreased pump or outward Na+,K+ cotransport activity may lead hypertensive subjects to a similar increase in cell Na+ (and Ca2+) content in the vascular wall.

Influence of membrane sodium transport upon the relation between blood lead and blood pressure in a general male population.

Five red blood cell cation transport systems (RBCTS), together with blood lead level and blood pressure, were measured in 129 male adult subjects who were not occupationally exposed to lead or subsequent to a course of treatment for hypertension. Blood lead was positively related with systolic blood pressure, and to a lesser degree with diastolic blood pressure. Blood lead was found significantly negatively related to one of the RBCTS, Na+,K+ cotransport, and in addition, Na+,K+ cotransport appeared negatively related to blood pressure. Final results showed that blood lead no longer accounts for an increase in systolic blood pressure when Na+,K+ cotransport was taken into account; the same trend was observed with diastolic blood pressure. These findings suggest that a blood lead-related Na+,K+ cotransport impairment could explain the blood pressure increase observed to parallel the blood lead increase.

Sample size calculations for risk equivalence testing in pharmacoepidemiology.

Equivalence testing has been widely discussed and is commonly used in pharmacokinetics (bioequivalence) and clinical trials (therapeutic equivalence). It can also be applied to pharmacoepidemiology, where the aim may be to test with a known risk (one-group design) or with another drug (two-group design). Whether the approach is two-sided or one-sided, predefined equivalence limits are required. The definition of the equivalence region can be based on either risk difference or risk ratio. Risk equivalence testing is complicated by the binary nature of the outcome, its low frequency, and by the absence of commonly defined equivalence limits for differences or ratios. In this context, we consider usable formulae for sample sizes. In most cases, at least when the risk studied is large enough (above 1/1,000), it appears that these formulae result in sample sizes that may be acceptable for practical purposes. For example, demonstrating equivalence with a known risk of 0.01, a 20% maximal risk difference, and a one-sided test (alpha = 0.05 and beta = 0.2) requires: under the one-group design (known risk), 15,309 patients; and under the two-group design, 30,617 patients per group. This approach is the appropriate way to conclude equivalence, rather than the commonly used approach of difference testing and concluding equivalence when the null hypothesis of equality is not rejected.

Power and weakness of spontaneous reporting: a probabilistic approach.

It has been clearly demonstrated that spontaneous reporting remains one of the best ways for picking up new adverse drug reactions (ADRs) once a drug is on the market. The probability of revealing a new ADR by spontaneous reporting was studied as a function of reporting rate, strength of drug-event association (relative risk), background incidence of the event and number of patients treated. The model included determination of (i) the probability of reporting at least one drug-event association case and (ii) the overall probability of concluding that the drug-event association is not coincidental. Both probabilities were generally low. The results suggest that the identification of a new risk by spontaneous reporting implies a strong association between the drug treatment and the occurrence of the event.

Estimation of risk as a function of risk factors.

This paper describes a model which makes allowance for unequal follow-up times in estimating the risk as a function of risk factors. It is the usual exponential model with an instantaneous risk which is assumed to be an exponential function of the risk factors. Computing methods and an extension of the model are given.

Correlated nondifferential misclassifications of disease and exposure: application to a cross-sectional study of the relation between handedness and immune disorders.

In cross-sectional studies, misclassifications of exposure and of health status may be related. For instance some subjects may tend to overreport both exposure and disease. A misclassification is said to be nondifferential if the sensitivity and the specificity which characterize it do not depend on the true status of the subjects for the other variables. Nondifferential misclassifications of two dichotomic variables may be correlated if the probability of being misclassified for one of them depends on the presence of an error of classification for the second one. Models are presented to estimate the bias induced by correlated nondifferential misclassifications on an odds ratio whose true value is unity. For most usual situations, when the great majority of the subjects are healthy and nonexposed, the influence of overreporting is shown to be larger than that of underreporting. It appears to be relatively easy to find a spurious, but significant, relationship. Real data are analysed to show that the potential consequences of correlated nondifferential misclassifications are not purely theoretical. In a sample of 1676 subjects from the general population we observed significant relations between left-hand shift and various aspects of health status: reporting a history of eczema, experience of a serious health problem in the past, experience of a serious health problem presently, use during the last month of analgesics or of drugs for circulatory problems, or digestion, consultation with a physiotherapist or hospitalization during the last year. These results, as with many similar ones previously reported, are highly suggestive of an information bias. They are less easily explained by biological hypotheses, e.g. Geschwind's theory of cerebral lateralization, than by correlated misclassifications resulting from overreporting of both the use of the left hand and the existence of some health problems by healthy right-handers. The modelling used in this report supports this hypothesis.

Case counting in epidemiology: limitations of methods based on multiple data sources.

BACKGROUND: The application of capture-recapture methods in epidemiology has been proposed as an alternative to field surveys. This methodology is important for the future of epidemiology and deserves a critical analysis. METHODS: This paper reviews conditions for applying the capture-recapture models to epidemiological data, taking into account practical considerations, in particular the problem of case definition. RESULTS: The underlying assumptions are particularly restrictive resulting in a theoretical limitation of their applicability. In spite of the statistical developments designed to overcome these difficulties, the practical conditions for using the existing lists are often not fulfilled (availability, confidentiality). The major restriction is on the quality of the data which are often far below the standards required in specific prevalence surveys and which may differ between lists. This may result in a dramatic lack of specificity. The definition of the virtual subgroup of patients missing in all lists as generated by the statistical procedure, is questionable particularly when counting living patients. Field studies would be necessary for validation. CONCLUSIONS: In some particular situations (e.g. deceased patients, rare diseases), this methodology may provide a useful approximation to the number of ill subjects events, but users should be aware of their poor specificity. It can also be useful to complement data from surveillance systems by careful cross-checking with independent sources of information. Currently, this method cannot, in any way, replace direct population prevalence or incidence surveys.

Short-term effects of sulphur dioxide pollution on mortality in two French cities.

To assess the short-term effects of sulphur dioxide (SO2) atmospheric pollution on mortality a study was conducted in two large French cities, using daily measures of pollution and mortality. A statistically significant association between daily SO2 pollution and respiratory deaths up to 10 days later was shown in both cities for both male and female populations together in the age group 65 years and over. No coherent results were found between SO2 pollution and cardiovascular deaths, or between suspended particulates and either respiratory or cardiovascular deaths. Particular emphasis was put on the use of correct statistical procedures using time series analysis and on the comparison of the part played by SO2 or suspended particulates on mortality.

Twelve years spirometric changes among Paris area workers.

The effects of smoking habits, socio-occupational factors and respiratory symptoms in the development of airflow obstruction have been studied in a working population of 575 men aged 30-54 in 1960 and surveyed in 1960 and 1972. On average, FEV1 decreased by 47 ml/annum. Apart from FEV1 level, which reflects loss since the beginning of adult life, three factors were independently related to FEV1 slope: tobacco consumption, occupational exposure and social class. The decrease of FEV1 with smoking was dose related and decelerated among those who stopped smoking. This follow-up study ruled against phlegm as a causal factor of early stage airflow obstruction, although its role is not excluded at later stages.

Blood cells and alcohol consumption with special reference to smoking habits.

In the course of the Paris study on risk factors of cardiovascular disease in a large professional group, 7710 active and apparently healthy men aged between 48 and 54 were examined. This study measured the relationship between clinical abnormalities suggesting alcoholic liver disease (ALD) and the following blood parameters: white (WBC) and red (RBC) blood cell counts, haematocrit (H), and mean corpuscular volume (MCV), the former computed as H/RBC ratio. A subsequent analysis was performed on a random sample of 485 subjects without ALD who were questioned on their daily average alcohol consumption. Each subject was classified as ;smoker' or ;non-smoker' according to his daily tobacco consumption for the last five years. Analysis of the data confirmed that smoking and alcohol were related to the blood parameters; but, according to smoking habit, different relationships between alcohol consumption (or ALD) and MCV, RBC, or WBC counts were found: for smokers, RBC count significantly decreased and MCV increased with alcohol consumption (or ALD); for non-smokers, WBC count significantly increased with alcohol consumption (or ALD). So, it would be of interest to consider the relation between alcohol and tobacco in interpreting possible changes in blood parameters and in formulating hypotheses on the mechanisms of their specific action.

[Smoking and serum alpha 1-antitrypsin in 1296 healthy men (author's transl)]. / alpha 1-Antitrypsine et tabac, une étude de 1296 hommes sains.

Serum alpha 1-antitrypsin (alpha 1AT) was measured by radial immunodiffusion in 1296 healthy men aged 18--50 years. Other biological criteria, including leukocyte count and alpha 2-globulins were measured and the subjects were given a detailed questionnaire on their smoking habits. Results showed a very strong positive relationship between smoking and serum alpha 1AT: the heavy smokers had a serum alpha 1AT 20% higher than the non-smokers, and among subjects who stopped smoking, the level returned rapidly to normal. There were also close interrelationships between serum alpha 1AT, smoking, leukocyte count and a alpha 2-globulins. A discussion of these results is presented.

Environmental exposure to cadmium and human birthweight.

Fetal toxicity of cadmium (Cd) is well documented in rodents. However, little information is available regarding the human fetus. To investigate the effect of low levels of Cd on the human placenta and the consequences on birthweight, we conducted a study of 102 mothers and their newborns in an obstetrical care unit. Placental and hair samples were collected at delivery to determine Cd concentrations. The main finding of this study was the relationship between a decrease in birthweight and an increase of newborn hair Cd which varied in the presence of placental calcification. In cases of parenchymal calcifications, placental Cd levels were higher (Wilcoxon test, P < 0.05) and newborn hair Cd levels were lower (Wilcoxon test, P < 0.01) than in the absence of calcification. These relationships remained significant even after taking into account smoking habits and gestational age. In the presence of calcification, an increase in the level of Cd in newborn hair was related to a decrease in birthweight which was independent of placental Cd concentration (rpartial = -0.49, P < 0.01). In the absence of calcification, a decrease in birthweight was observed for the upper values of newborn hair Cd (r = -0.44, P < 0.05 when Cd > or = 0.3 ppm). The difference in birthweight between infants in the first and last quartiles of newborn hair Cd was 472 g in cases of calcifications and 122 g in the absence of calcification. Other placental parameters were not significantly related to placental Cd concentration.

What happens to depressed men? Application of the Stirling County criteria.

In a recent issue of the Harvard Review of Psychiatry, results from the Stirling County Study showed that the prevalence and incidence rates of depression were similar in men and women when "gender-fair" criteria were used and help-seeking was not required. We attempted to replicate these findings by applying the criteria for depression from the Stirling County Study to two national and six international epidemiologic surveys conducted in the 1980s and 1990s. Depression was defined as dysphoric mood and disturbances of sleep, appetite, and energy, with at least a mild degree of impairment. The rates of depression were computed using this algorithm with data from the US Epidemiologic Catchment Area Study, conducted in the 1980s, the US National Comorbidity Survey, conducted in the 1990s, and independent community surveys from Canada, Puerto Rico, France, Taiwan, Korea, and New Zealand. For the US studies, these rates were recalculated after persons seeking treatment were removed from the analyses, where such data were available. Using Stirling County Study criteria, the lifetime prevalence rate of depression remains approximately twice as high in women as in men cross-nationally, except in Puerto Rico. Excluding help-seeking as a criterion and controlling for birth cohort do not change the findings. The Stirling County findings on absence of a sex difference in rates of depression using "gender-fair" criteria may be due to methodological variance in the collection of data, sample size, or the social and/or genetic uniqueness of the Atlantic Canadian community.

Vitamin B12 among parturients and their newborns and its relationship with birthweight.

Vitamin B12 (Cobalamin) is an essential nutrient in the diet of humans, particularly during pregnancy, nevertheless very few epidemiological studies have been reported, particularly concerning variation factors. The purpose of this study is to assess the role of vitamin B12 on birthweight after taking into account potential confounders, such as obstetrical, socioeconomic, and biological factors which will be identified. This study was conducted on 188 single births occurring during a 5-month period in an obstetrical care unit in Paris. Vitamin B12 plasma levels and folate plasma levels of mothers and cords along with haematological parameters were measured. Social and obstetrical features of the mothers as well as their tobacco exposure and alcohol consumption were recorded. Cord blood vitamin B12 levels were highly correlated with maternal levels (r = 0.63, P less than 0.001) and were 2-3-fold higher. Three variation factors of vitamin B12 were identified: maternal age, ethnicity and tobacco exposure. Negative correlations between birthweight and vitamin B12 levels were observed only among the smoker group (r mothers = -0.46, P less than 0.05 and r cords = -0.42, P less than 0.05). After adjustment for ethnicity and parity, birthweight remained negatively linked to vitamin B12 in smokers. This relationship could suggest that the availability of vitamin B12 for fetal development depends on certain biological factors present only in mothers who smoked. We hypothesized this relationship could be explained, in part, by lipid metabolism, particular to smokers.