Estimation of the salt intake distribution of Dutch kidney transplant recipients using 24-h urinary sodium excretion: the potential of external within-person variance.

BACKGROUND: There is growing interest in assessing a population's prevalence of inadequate nutrient intake using biomarkers. However, within-person variation is generally ignored because repeated data collections are considered costly and burdensome. OBJECTIVES: The study aimed to show the importance of estimating, from repeated 24-h urine collections, a population's habitual salt intake and to explore the potential of using the ratio of within-person variance to total variance from an external source (W:T variance) with single 24-h urine collection. METHODS: Salt intake was predicted from data for 24-h urinary sodium excretion in adult kidney transplant recipients in 1992-1997 (n = 432) and 2006-2011 (n = 1159). The salt intake distribution of single-day measurements was compared with estimates from multiple 24-h urine collections, which were statistically corrected for within-person variance. Habitual salt intake was also estimated using single-day measurements and external variance estimates. From each distribution, the proportion below specified cut-off values was estimated. RESULTS: In 2006-2011 the average habitual salt intake was 10.6 g/d (men) and 8.5 g/d (women); in 1992-1997 these values were 8.6 g/d and 7.5 g/d, respectively. The proportion with salt intake <6 g/d was 5% and 13% in 2006-2011 and 22% and 28% in 1992-1997, respectively, for men and women. Correction for within-person variance significantly narrowed the salt intake distribution-the proportion with salt intake <6 g/d was overestimated by 3-13 percentage points using single-day data. Sensitivity analyses showed the importance of a sufficient sample size for estimating variance components. Variation of the W:T variance showed up to 40 percentage points deviation in the proportion with intakes below a specified cut-off value. CONCLUSIONS: To estimate a population's salt intake distribution, it is important to correct 24-h urinary sodium excretion for within-person variance. Predicting habitual salt intake distribution using single-day measurements with external variances is promising; a sensitivity analysis is recommended to show the effect of different external variances.

Decreased, but still sufficient, iodine intake of children and adults in the Netherlands.

Sufficient I intake is important for the synthesis of thyroid hormones, which play an important role in normal growth and development. Our aim was to estimate habitual I intake for the Dutch population and the risk of inadequate or excessive intakes. Further, we aimed to provide an insight into the dietary sources of I and the association with socio-demographic factors. Data from the Dutch National Food Consumption Survey 2007-2010 (n 3819; 7-69 years), and from the Dutch food and supplement composition tables were used to estimate habitual I intake with a calculation model. Contribution of food groups to I intake were computed and multiple linear regression was used to examine associations of intakes with socio-demographic factors. A total of ≤2 % of the population had an intake below the estimated average requirement or above the upper level. The main sources of I were bread containing iodised salt (39 %), dairy products (14 %) and non-alcoholic drinks (6 %). I intake (natural sources only, excluding iodised salt and supplements) was positively associated with (parental) education, which could at least partly be attributed to a higher consumption of dairy products. Among children, the consumption of bread, often containing iodised bakery salt, was positively associated with parental education. The I intake of the Dutch population (7-69 years) seems adequate, although it has decreased since the period before 2008. With the current effort to reduce salt intake and changing dietary patterns (i.e. less bread, more organic foods) it is important to keep a close track on the I status, important sources and potential risk groups.

Estimating US dairy clinical disease costs with a stochastic simulation model.

A farm-level stochastic model was used to estimate costs of 7 common clinical diseases in the United States: mastitis, lameness, metritis, retained placenta, left-displaced abomasum, ketosis, and hypocalcemia. The total disease costs were divided into 7 categories: veterinary and treatment, producer labor, milk loss, discarded milk, culling cost, extended days open, and on-farm death. A Monte Carlo simulation with 5,000 iterations was applied to the model to account for inherent system variation. Four types of market prices (milk, feed, slaughter, and replacement cow) and 3 herd-performance factors (rolling herd average, product of heat detection rate and conception rate, and age at first calving) were modeled stochastically. Sensitivity analyses were conducted to study the relationship between total disease costs and selected stochastic factors. In general, the disease costs in multiparous cows were greater than in primiparous cows. Left-displaced abomasum had the greatest estimated total costs in all parities ($432.48 in primiparous cows and $639.51 in multiparous cows). Cost category contributions varied for different diseases and parities. Milk production loss and treatment cost were the 2 greatest cost categories. The effect of market prices were consistent in all diseases and parities; higher milk and replacement prices increased total costs, whereas greater feed and slaughter prices decreased disease costs.

Comparison of the ISU, NCI, MSM, and SPADE Methods for Estimating Usual Intake: A Simulation Study of Nutrients Consumed Daily.

Various methods are available for estimating usual dietary intake distributions. Hence, there is a need for simulation studies to compare them. The methods Iowa State University (ISU), National Cancer Institute (NCI), Multiple Source Method (MSM) and Statistical Program to Assess Dietary Exposure (SPADE) were previously compared in another study, but some results were inconclusive due to the small number of replications used in the simulation. Seeking to overcome this limitation, the present study used 1000 simulated samples for 12 different scenarios to compare the accuracy of estimates yielded by the aforementioned methods. The focus is on scenarios that exhibited the most uncertainty in the conclusions of the mentioned study above, i.e., scenarios with small sample sizes, skewed intake distributions, and large ratios of the between- and within-person variances. Bias was used as a measure of accuracy. For scenarios with small sample sizes (n = 150), the ISU, MSM and SPADE methods generally achieved more accurate estimates than the NCI method, particularly for the 10th and 90th percentiles. The differences between methods became smaller with larger sample sizes (n = 300 and n = 500). With few exceptions, the methods were found to perform similarly.

Fibromyalgia: management strategies for primary care providers.

AIMS: Fibromyalgia (FM), a chronic disorder defined by widespread pain, often accompanied by fatigue and sleep disturbance, affects up to one in 20 patients in primary care. Although most patients with FM are managed in primary care, diagnosis and treatment continue to present a challenge, and patients are often referred to specialists. Furthermore, the lack of a clear patient pathway often results in patients being passed from specialist to specialist, exhaustive investigations, prescription of multiple drugs to treat different symptoms, delays in diagnosis, increased disability and increased healthcare resource utilisation. We will discuss the current and evolving understanding of FM, and recommend improvements in the management and treatment of FM, highlighting the role of the primary care physician, and the place of the medical home in FM management. METHODS: We reviewed the epidemiology, pathophysiology and management of FM by searching PubMed and references from relevant articles, and selected articles on the basis of quality, relevance to the illness and importance in illustrating current management pathways and the potential for future improvements. RESULTS: The implementation of a framework for chronic pain management in primary care would limit unnecessary, time-consuming, and costly tests, reduce diagnostic delay and improve patient outcomes. DISCUSSION: The patient-centred medical home (PCMH), a management framework that has been successfully implemented in other chronic diseases, might improve the care of patients with FM in primary care, by bringing together a team of professionals with a range of skills and training. CONCLUSION: Although there remain several barriers to overcome, implementation of a PCMH would allow patients with FM, like those with other chronic conditions, to be successfully managed in the primary care setting.

SPADE, a new statistical program to estimate habitual dietary intake from multiple food sources and dietary supplements.

BACKGROUND: For the evaluation of both the adequacy of intakes and the risk of excessive intakes of micronutrients, all potential sources should be included. In addition to micronutrients naturally present in foods, micronutrients can also be derived from fortified foods and dietary supplements. In the estimation of the habitual intake, this may cause specific challenges such as multimodal distributions and heterogeneous variances between the sources. OBJECTIVE: We present the Statistical Program to Assess Dietary Exposure (SPADE) that was developed to cope with these challenges in one single program. METHOD: Similar to other methods, SPADE can model habitual intake of daily and episodically consumed dietary components. In addition, SPADE has the option to model habitual intake from dietary supplements. Moreover, SPADE offers models to estimate habitual intake distributions from different sources (e.g., foods and dietary supplements) separately and adds these habitual intakes to get the overall habitual intake distribution. The habitual intake distribution is modeled as a function of age, and this distribution can directly be compared with cutoff values to estimate the proportion above or below. Uncertainty in the habitual intake distribution and in the proportion below or above a cutoff value is quantified with ready-for-use bootstrap and provides 95% CIs. RESULTS: SPADE is implemented in R and is freely available as an R package called SPADE.RIVM. The various features of SPADE are illustrated by the estimation of the habitual intake distribution of folate and folic acid for women by using data from the Dutch National Food Consumption Survey 2007-2010. The results correspond well with the results of existing programs. CONCLUSION: SPADE offers new features to existing programs to estimate the habitual intake distribution because it can handle many different types of modeling with the first-shrink-then-add approach.

Predicting urinary creatinine excretion and its usefulness to identify incomplete 24 h urine collections.

Studies using 24 h urine collections need to incorporate ways to validate the completeness of the urine samples. Models to predict urinary creatinine excretion (UCE) have been developed for this purpose; however, information on their usefulness to identify incomplete urine collections is limited. We aimed to develop a model for predicting UCE and to assess the performance of a creatinine index using para-aminobenzoic acid (PABA) as a reference. Data were taken from the European Food Consumption Validation study comprising two non-consecutive 24 h urine collections from 600 subjects in five European countries. Data from one collection were used to build a multiple linear regression model to predict UCE, and data from the other collection were used for performance testing of a creatinine index-based strategy to identify incomplete collections. Multiple linear regression (n 458) of UCE showed a significant positive association for body weight (ß = 0·07), the interaction term sex × weight (ß = 0·09, reference women) and protein intake (ß = 0·02). A significant negative association was found for age (ß = -0·09) and sex (ß = -3·14, reference women). An index of observed-to-predicted creatinine resulted in a sensitivity to identify incomplete collections of 0·06 (95 % CI 0·01, 0·20) and 0·11 (95 % CI 0·03, 0·22) in men and women, respectively. Specificity was 0·97 (95 % CI 0·97, 0·98) in men and 0·98 (95 % CI 0·98, 0·99) in women. The present study shows that UCE can be predicted from weight, age and sex. However, the results revealed that a creatinine index based on these predictions is not sufficiently sensitive to exclude incomplete 24 h urine collections.

A three-part, mixed-effects model to estimate the habitual total vitamin D intake distribution from food and dietary supplements in Dutch young children.

Statistical modeling of habitual micronutrient intake from food and dietary supplements using short-term measurements is hampered by heterogeneous variances and multimodality. Summing short-term intakes from food and dietary supplements prior to simple correction for within-person variation (first add then shrink) may produce estimates of habitual total micronutrient intake so badly biased as to be smaller than estimates of habitual intake from food sources only. A 3-part model using a first shrink then add approach is proposed to estimate the habitual micronutrient intake from food among nonsupplement users, food among supplement users, and supplements. The population distribution of habitual total micronutrient intake is estimated by combining these 3 habitual intake distributions, accounting for possible interdependence between Eq. 2 and 3. The new model is an extension of a model developed by the USA National Cancer Institute. Habitual total vitamin D intake among young children was estimated using the proposed model and data from the Dutch food consumption survey (n = 1279). The model always produced habitual total intakes similar to or higher than habitual intakes from food sources only and also preserved the multimodal shape of the observed total vitamin D intake distribution. This proposed method incorporates several sources of covariate information that should provide more precise estimates of the habitual total intake distribution and the proportion of the population with intakes below/above cutpoint values. The proposed methodology could be useful for other complex situations, e.g. where high concentrations of micronutrients appear in episodically consumed foods.

the potential of AGE MODE, an age-dependent model, to estimate usual intakes and prevalences of inadequate intakes in a population.

Dietary intake data often stem from short-term measurements. However, for dietary assessment, generally the habitual intake distribution is of interest. Currently, habitual intake distributions are often estimated separately for subgroups of gender and age and do not take into account the variation in intake caused by age within age groups. Therefore, we developed an age-dependent dietary assessment model, which was demonstrated and tested using folate intakes from the third Dutch National Food Consumption Survey, conducted in 1997/98. The proposed model produced estimates of the mean habitual intake and intake percentiles as a function of age. The methodology has clear advantages in estimating habitual intakes in children. Also, given the large variation in intakes of several dietary components, estimated habitual intakes produced by other methods may have low precision and be less reliable if numbers are small. In our age-dependent model, all available data can be used to estimate the parameters of the habitual intake distribution, improving the precision of the estimates, and providing consistent estimates for a larger population sample as no subgroups need to be created. Although the model may still be further developed, the feature of age dependency shows clear advantages above methods currently used to estimate habitual intakes.

Automated detection of infectious disease outbreaks: hierarchical time series models.

The purpose of infectious disease surveillance is to inform the public health policy makers on the incidence and trends of infectious diseases and to trigger appropriate actions to control infectious disease outbreaks. The enormous amount of data collected with automated laboratory-based surveillance systems require automated algorithms for detecting unexpected aberrations that may signal infectious disease outbreaks. In this paper, we explore the potential of hierarchical time series models to detect deviations from expected incidence. As these count data are extremely noisy it can be expected that these models are suitable to detect signal from noise and accommodate for possible autocorrelation. The proposed procedure consists of three steps; (1) the model parameters are estimated by empirical Bayes on a training period of, e.g. a year; (2) the expected values are updated for small time steps (e.g. daily) as new data arrive; (3) threshold levels are updated conditionally on the past expected values and an alarm is triggered when the threshold level is exceeded. To test the potential of the models we estimated sensitivity, specificity and timeliness on simulated time series and compared the results with an alternative approach of a linear regression model adjusted for trends and season. We also used two observed series for Rubella notifications and Salmonella infections and compared our findings with the expert opinions on these series. The hierarchical time series models approach shows high sensitivity and specificity and correctly identifies outbreaks at an early stage. This, in our opinion, makes the proposed model a reliable tool for adequate automated detection of infectious disease outbreaks.

Ziprasidone: a new atypical antipsychotic.

This paper reviews the clinical pharmacology, efficacy and safety of the new atypical antipsychotic, ziprasidone. All published citations regarding ziprasidone were retrieved and reviewed using a MEDLINE search (completed for citations to early 2001). In addition, abstracts from recent scientific meetings presenting data not yet published were reviewed. Like other new antipsychotic medications, ziprasidone fits the profile of an atypical agent, exerting efficacy in positive and negative symptoms of psychosis, as well as affective symptoms, with a low risk of neurological and neuroendocrinological side effects. Unlike newer agents, it does not appear to be associated with weight gain in most patients.

Psychogenic excoriation. Clinical features, proposed diagnostic criteria, epidemiology and approaches to treatment.

Psychogenic excoriation (also called neurotic excoriation, acne excoriée, pathological or compulsive skin picking, and dermatotillomania) is characterised by excessive scratching or picking of normal skin or skin with minor surface irregularities. It is estimated to occur in 2% of dermatology clinic patients and is associated with functional impairment, medical complications (e.g. infection) or substantial distress. Psychogenic excoriation is not yet recognised in the DSM. We propose preliminary operational criteria for its diagnosis that take into account the heterogeneity of behaviour associated with psychogenic excoriation and allow for subtyping along a compulsivity-impulsivity spectrum. Psychiatric comorbidity in patients with psychogenic excoriation, particularly mood and anxiety disorders, is common. Patients with psychogenic excoriation frequently have comorbid disorders in the compulsivity-impulsivity spectrum, including obsessive-compulsive disorder, body dysmorphic disorder, substance use disorders, eating disorders, trichotillomania, kleptomania, compulsive buying, obsessive-compulsive personality disorder, and borderline personality disorder. There are few studies of the pharmacological treatment of patients with psychogenic excoriation. Case studies, open trials and small double-blind studies have demonstrated the efficacy of selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors in psychogenic excoriation. Other pharmacological treatments that have been successful in case reports include doxepin, clomipramine, naltrexone, pimozide and olanzapine. There are no controlled trials of behavioural or psychotherapeutic treatment for psychogenic excoriation. Treatments found to be effective in case reports include a behavioural technique called 'habit reversal'; a multicomponent programme consisting of self-monitoring, recording of episodes of scratching, and procedures that produce alternative responses to scratching; and an 'eclectic' psychotherapy programme with insight-oriented and behavioural components.

Bipolar disorder.

Bipolar disorder (manic-depressive illness) is a common, recurrent, and severe psychiatric disorder that affects 1% to 3% of the US population. The illness is characterized by episodes of mania, depression, or mixed states (simultaneously occurring manic and depressive symptoms). Bipolar disorder frequently goes unrecognized and untreated for many years without clinical vigilance. New screening tools have been developed to assist physicians in making the diagnosis. Fortunately, several medications are now available to treat the acute mood episodes of bipolar disorder and to prevent further episodes with maintenance treatment.

Placebo effect in randomized, controlled studies of acute bipolar mania and depression.

Randomized, double-blind, placebo-controlled, parallel group clinical trials have been the standard methodology for establishing the efficacy of new treatments for patients with bipolar disorder in manic, mixed, or depressive episodes. We examine the placebo response rate in acute treatment trials of acute mania (and mixed states) and bipolar depression. Also addressed are potential variables associated with placebo response, strategies to minimize placebo response, the optimum duration of placebo-controlled acute treatment trials, possible alternatives to the use of placebo, and the ramifications of these issues with regard to the design of studies in children, adolescents, and older adults with bipolar disorder.

Placebo effect in randomized, controlled maintenance studies of patients with bipolar disorder.

The prevention of mood episodes is an important goal of the maintenance treatment of patients with bipolar disorder. The rate of relapse on placebo compared with that on active treatment is an important issue in the design of future clinical trials of maintenance treatment. We examine the range and time course of placebo relapse rates in studies of patients with bipolar I disorder. In addition, we address the potential variables associated with placebo response, strategies to minimize placebo response, the optimum duration of placebo-controlled maintenance trials, possible alternatives to placebo control groups, and the impact of these considerations in maintenance studies of children, adolescents, and older adults with bipolar disorder.

Antidepressant treatment of fibromyalgia. A meta-analysis and review.

Fibromyalgia is a common musculoskeletal pain disorder associated with mood disorders. Antidepressants, particularly tricyclics, are commonly recommended treatments. Randomized, controlled trials of antidepressants for treatment of fibromyalgia were reviewed by methodology, results, and potential predictors of response. Twenty-one controlled trials, 16 involving tricyclic agents, were identified; 9 of these 16 studies were suitable for meta-analysis. Effect sizes were calculated for measurements of physician and patient overall assessment, pain, stiffness, tenderness, fatigue, and sleep quality. Compared with placebo, tricyclic agents were associated with effect sizes that were substantially larger than zero for all measurements. The largest improvement was associated with measures of sleep quality; the most modest improvement was found in measures of stiffness and tenderness. Further studies are needed utilizing randomized, double-blind, placebo-controlled, parallel designs with antidepressants administered at therapeutic dose ranges, using standardized criteria for fibromyalgia and systematically assessed for co-occurring psychiatric illness.

Health-related quality of life using the SF-36 in patients with bipolar disorder compared with patients with chronic back pain and the general population.

BACKGROUND: The purpose of this study was to assess and compare the health-related quality of life of patients with bipolar disorder and chronic back pain and, in turn, to compare these results with those previously generated for the general population. METHODS: Subjects were patients with bipolar disorder (n=44), a comparison group of chronic back pain patients (n=30), and a population-based control sample (n=2,474). Health-related quality of life was assessed using the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36), a self-administered questionnaire in which lower scores are indicative of greater impairment. RESULTS: Patients with bipolar disorder had lower mean scores than the general population on all scales except Physical Functioning. Bipolar patients had significantly higher scores than chronic back pain patients in the categories of Physical Functioning, Role Limitations--Physical, Bodily Pain, and Social Function. There were no significant differences between bipolar disorder and chronic back pain groups in the Mental Health and Role Limitations - Emotional categories. LIMITATIONS: The results of the study are limited by the relatively small sample sizes of the bipolar and back pain patient groups. CONCLUSIONS: Patients with bipolar disorder had substantial impairment in health-related quality of life in comparison with the general population. Bipolar patients were less compromised in areas of physical and social functioning than chronic back pain patients but had similar impairment in mental health.