Comparing SSRI Treatment Costs for Depression Using Retrospective Claims Data: The Role of Nonrandom Selection and Skewed Data

Background and Objectives: Since conventional randomized clinical trials often do not reflect the real world circumstances of prescribing behavior and patient outcomes, the use of retrospective administrative claims databases (RACD) has become more common in treatment cost comparisons among alternative pharmaceutical compounds. Several recent RACD studies have compared treatment costs for depressed patients prescribed SSRIs such as fluoxetine, sertraline and paroxetine. These cost comparisons have reached mixed conclusions. To begin to explain and reconcile the mixed SSRI cost comparison evidence, we undertake a variety of alternative multivariate analyses using a publicly available RACD.
Methods and Data: The 1995 to 1996 data encompasses a time period when all three SSRIs had become well-established agents. We report and compare results from multivariate linear regressions, logistic regressions, ordered probits and sample selectivity models, and examine robustness when adjustments are made for outlier observations and skewed distributions.
Results and Conclusions: While choice of initial SSRI is nonrandom, the effect of sample selectivity on total depression-related and total health care expenditure is neutral across SSRIs. Although most cost measures are numerically greatest for fluoxetine, depression-related outpatient and hospitalization costs do not significantly differ by choice of initial SSRI. These findings are robust to alternative assumptions, specifications, and procedures. Antidepressant medication costs, however, are significantly higher when fluoxetine is the initial SSRI rather than sertraline or paroxetine, reflecting the larger proportion of fluoxetine patients prescribed a daily dosage of two or more capsules. Both total depression-related and total health care log–transformed costs are significantly lower for sertraline than fluoxetine.     

Mammography casting-type calcification and risk of local recurrence in DCIS: analyses from a randomised study

Background:

We studied the association between mammographic calcifications and local recurrence in the ipsilateral breast.

Methods:

Case-cohort study within a randomised trial of radiotherapy in breast conservation for ductal cancer in situ of the breast (SweDCIS). We studied mammograms from cases with an ipsilateral breast event (IBE) and from a subcohort randomly sampled at baseline. Lesions were classified as a density without calcifications, architectural distortion, powdery, crushed stone-like or casting-type calcifications.

Results:

Calcifications representing necrosis were found predominantly in younger women. Women with crushed stone or casting-type microcalcifications had higher histopathological grade and more extensive disease. The relative risk (RR) of a new IBE comparing those with casting-type calcifications to those without calcifications was 2.10 (95% confidence interval (CI) 0.92–4.80). This risk was confined to in situ recurrences; the RR of an IBE associated with casting-type calcifications on the mammogram adjusted for age and disease extent was 16.4 (95% CI 2.20–140).

Conclusion:

Mammographic appearance of ductal carcinoma in situ of the breast is prognostic for the risk of an in situ IBE and may also be an indicator of responsiveness to RT in younger women.     

Influence of pH and storage time on the sorption and solubility behaviour of three composite resin materials

OBJECTIVES: The aim of this study was to determine whether pH and time has any influence on the sorption and solubility behaviour of composite resin materials stored in a buffer solution. METHODS: Three hybrid composite restorative resin materials (Spectrum, Z-100 and ArtGlass) with different matrix structure and filler composition were studied. One hundred and twenty specimens of each material were produced according to ISO 4049. The materials were stored in McIlvain's buffer solution at different pH (4, 6 and 8) at 1, 7, 60 and 180 days. pH measurements were carried out before and after completed storage. RESULTS: Time had a significant influence on the sorption and solubility behaviour of the composite resin materials tested. One of the materials Z-100 showed a significant mass increase and/or decrease depending on the pH of the solution. The material Spectrum was significantly influenced by pH, resulting in different sorption depending on the pH of the solution. CONCLUSIONS: Time of storage was important for the sorption and solubility behaviour of the composite resin materials tested. Comparison of solubility for one of the materials showed twice as high values in the present study as previously reported when distilled water was used as storage medium. pH in the solution seems to have an influence on the sorption and solubility behaviour of composite resin materials. The sensitivity of the sorption and solubility behaviour to time and pH of the materials tested seems to be related to the hydrophilicity of the matrix and the chemical composition of the filler.     

A study of the reproducibility of the functional denture space with a dynamic impression technique.

A study was made on four patients to determine the reproducibility of the outer form of the buccal and lingual flanges of a complete lower denture as developed by functional movements of the surrounding tissues. 1. Two dentists participated in the study to find out the operator effect when making impressions for the functional form of the flanges. 2. Two tissue-conditioning impression materials were used to determine if the characteristics of the impression material had any effect on the final form. 3. The impression materials were applied to the denture flanges by two different methods. 4. The impressions were placed in a mitre box, stabilized with plaster, and sectioned in the molar, premolar, and incisor regions. This provided five cut surfaces for measuring. 5. Each section was measured at five to six representative distances. 6. The differences in the flange form measurement and the distances among the impressions made with the same technique and material were small, and the reproducibility can be considered clinically acceptable. 7. There were statistically significant differences in the flange form measurement distances among the different materials and method of application of the material.     

Effects of intense chewing on some parameters of masticatory function.

This study recorded the influence of 30 minutes of intense chewing on the masticatory function in 17 healthy subjects. Functional recordings of mandibular movements and velocity, measurements of masticatory efficiency, maximal occlusal force, and occlusal force endurance time were performed before and after functional stimulation and finally in a 2- to 5-day follow-up registration. After intense chewing, a substantially decreased masticatory cycle and occlusal level phase duration were recorded. No major mandibular displacements or changes in velocity were recorded. Masticatory efficiency and maximal occlusal force in the incisal region diminished after 30 minutes of intense chewing. Occlusal force endurance time was also lowered after intense chewing. The measurements were close to their original values at the follow-up. Intense chewing had various short-term effects on masticatory function, including a significant reduction of masticatory efficiency, maximal occlusal force, occlusal force endurance, and masticatory cycle duration.     

Characteristics of masticatory mandibular movements and velocity in growing individuals and young adults

Studies of the development of mastication in the normal growing individual have received little attention in the literature. The aim of this study was to determine whether changes in oral motor function occurred during growth. Ninety healthy individuals with normal occlusion were divided into six groups of males and females, 9-10, 13-15, and 20-22 years of age. Oral motor function, with respect to mandibular displacement and velocity, was monitored with an opto-electronic method. The results revealed that the total duration of the masticatory cycle was not influenced by age or gender. However, the time distribution between the different phases was found to be influenced by the age factor, causing a longer opening time and a shorter closing time in the adults. In mastication, both mandibular displacement and the mandibular velocity in closing were less in females. A reduction of the masticatory opening velocity and an increase in closing velocity were observed with increasing age. Physiological maturation of the masticatory system due to central and peripheral changes and functional adjustments due to changes in dentition and skeletal growth may be the underlying reasons for our findings.     

Infrared fluorescence measurements – The influence of calibration frequency on longitudinal in vitro measurements with KaVo DIAGNOdentTM

With today's widespread use of fluoride, the nature of cavities has changed. Harder, and therefore more resistant enamel can many times conceal subsurface decay and the caries disease progresses, in many cases, for a prolonged period with low activity and slow progression. The change in pattern of the caries disease calls for a shift in treatment philosophy; the original maxim of ‘extension for prevention’ has been eschewed for a minimal intervention approach, although this approach is only effective if caries is diagnosed at an early stage. Incorrect diagnosis results in incorrect treatment decisions. In the current age of lower overall prevalence of decay and slow disease progression, the potential risk of unnecessary restorations is greater than the risk of missing early decay. As an adjunct to conventional caries diagnostic methods such as visual inspection and bitewing radiography, a need for objective quantitative detection methods is of high importance. KaVo DIAGNOdent^TM (KaVo Dental, Biberach, Germany) is a laser fluorescence device developed for caries detection and quantification as an adjunct to visual inspection and radiographic examination. The aim of this in vitro study was to investigate the stability of the instrument for longitudinal measurements. The study was carried out in two subsequent parts where measurements were performed in two series, with and without calibration. The material in Part I of the study comprised 30 extracted teeth with various stages of carious lesions measured with one DIAGNOdent^TM device. In Part II, two devices were used to determine their unanimity and measurements were performed on six fluorescence standards in order to minimize false positive readings. The first series in Part I, with only one initial calibration, showed a significant change over time: a linear trend with drifting towards lower readings (P < 0.001). In the second series, with frequent calibrations, no significant linear trend over time could be demonstrated (P = 0.09). Clinically relevant differences in mean value between the series of measurements were seen over time (without frequent calibration, 7.64; with frequent calibration 8.57). The mean value of readings from the series with frequent calibrations was approximately 1 unit higher throughout the study, and single observations were 1–6 units higher. Results from Part II showed a significant systematic over‐time difference between the factor ‘without’ and ‘with’ calibration (P = 0.0023) independent of which device that was used (P = 0.67). There was no significant difference between the devices, DDI and DDII (P = 0.14). The interaction, time × calibration, was significant (P < 0.000) with stable readings over time in the period ‘with calibration’, while the readings in the period ‘without calibration’ was drifting towards lower readings from day 1 and forward. From this in vitro study it was concluded that frequent calibration of DIAGNOdent^TM should be performed in order to obtain comparable data for longitudinal monitoring.     

Analysis of nanoparticle–protein coronas formed in vitro between nanosized welding particles and nasal lavage proteins

Welding fumes include agglomerated particles built up of primary nanoparticles. Particles inhaled through the nose will to some extent be deposited in the protein-rich nasal mucosa, and a protein corona will be formed around the particles. The aim was to identify the protein corona formed between nasal lavage proteins and four types of particles with different parameters. Two of the particles were formed and collected during welding and two were manufactured iron oxides. When nasal lavage proteins were added to the particles, differences were observed in the sizes of the aggregates that were formed. Measurements showed that the amount of protein bound to particles correlated with the relative size increase of the aggregates, suggesting that the surface area was associated with the binding capacity. However, differences in aggregate sizes were detected when nasal proteins were added to UF_WF and Fe₂O₃ particles (having similar agglomerated size) suggesting that yet parameters other than size determine the binding. Relative quantitative mass spectrometric and gel-based analyses showed differences in the protein content of the coronas. High-affinity proteins were further assessed for network interactions. Additional experiments showed that the inhibitory function of secretory leukocyte peptidase inhibitor, a highly abundant nasal protein, was influenced by particle binding suggesting that an understanding of protein function following particle binding is necessary to properly evaluate pathophysiological events. Our results underscore the importance of including particles collected from real working environments when studying the toxic effects of particles because these effects might be mediated by the protein corona.     

Dental anxiety in Iceland: an epidemiological postal survey

In this study, we examined the prevalence of specific (dental) phobia among a sample of the Icelandic population. In addition to dental anxiety we explored factors that could be related to dental anxiety. In the period 1972-73, a stratified sample of 1641 schoolchildren in Reykjavík was selected for a study on malocclusion, dental maturation and other factors. Twenty-two years later (1995), a postal survey conducted in this group looked at many variables relating to oral health, including orofacial pain, functional oral disorders, self-perception of dental and general appearance and need for orthodontic treatment. Out of 1529 individuals contacted, 1192 completed questionnaires were returned (response rate 78%). Questions based on DSM-IV criteria of specific (dental) phobia (DP) were included. Ninety-six participants reported that they had avoided dental treatment during the previous 6 months. Twenty-one respondents fulfilled DSM-IV criteria for specific (dental) phobia (DP) and 75 admitted to many symptoms of dental anxiety (DA). Specific (dental) phobia (DP) was more prevalent among women than among men. The divorced or widowed were most at risk, as were non-salaried respondents. Most respondents attributed the onset of their phobias to a specific painful or fearful experience. There was a significant difference between the total dentally anxious (TDA = DA + DP) and the not dentally anxious (NDA) with regard to sex (women--higher TDA) and marital status (divorced or widowed--higher TDA). The TDA had statistically fewer teeth than the NDA and received dental treatment less frequently.