Non-response did not affect prevalence estimates of asthma and respiratory symptoms - results from a postal questionnaire survey of the general population.

BACKGROUND: A high participation rate is warranted in order to ensure validity in surveys of the general population. However, participation rates in such studies have declined during the last decades. OBJECTIVE: To evaluate the reasons for and potential effects of non-response in a large population-based survey about asthma and respiratory symptoms in Northern Sweden. METHODS: Within the Obstructive Lung Disease In Norrbotten (OLIN) studies, a random sample of 12,000 adults aged 20-79 was invited to a postal questionnaire survey about asthma, allergic rhino-conjunctivitis and respiratory symptoms in 2016. Three reminders were sent. A random sample of 500 non-responders was invited to a telephone interview. RESULTS: The participation rate in the initial mailing was 41.4%, and 9.2%, 5.0%, and 2.6% in the subsequent three reminders and totally 58.3% (n = 6854) responded. Of 500 non-responders selected for telephone interviews, 320 were possible to reach and 272 participated. Male sex, younger age, and current smoking were associated with both late and non-response. The prevalence of asthma and most respiratory symptoms did not differ significantly between responders and non-responders while allergic rhino-conjunctivitis and smoking was more common among non-responders. Reminders increased the participation rate but did not alter risk ratios for smoking and occupational exposures. Reasons for non-response were mainly lack of time and having forgotten to answer. CONCLUSIONS: With a response rate of 58.3%, neither the prevalence estimates of asthma, respiratory symptoms nor the associations to risk factors were affected by non-response, while allergic rhino-conjunctivitis and smoking was underestimated in this Swedish population.

High incidence and persistence of airborne allergen sensitization up to age 19 years.

BACKGROUND: Longitudinal population-based studies about the natural history of allergic sensitization are rare. The aim was to study incidence and persistence of airborne allergen sensitization up to young adulthood and risk factors for early and late onset of sensitization. METHODS: All children aged 7-8 years in two municipalities in Northern Sweden were invited to a parental questionnaire and skin prick tests (SPTs) to ten airborne allergens, and 2148 (88%) participated. The protocol was repeated at age 11-12 and 19 years, and 1516 participated in all three examinations. RESULTS: Prevalence of any positive SPT increased from 20.6% at age 7-8 years to 30.6% at 11-12 years, and 42.1% at 19 years. Animals were the primary sensitizers at age 7-8 years, 16.3%, followed by pollen, 12.4%. Mite and mold sensitization was low. Mean annual incidence of any positive SPT varied between 2.8 and 3.4/100 per year, decreased by age for animal, and was stable for pollen. Sensitization before age 7-8 years was independently associated with family history of allergy, OR 2.1 (95% CI 1.6-2.8), urban living, OR 1.9 (95% CI 1.2-2.9), and male sex, OR 1.3 (95% CI 1.0-1.7), and negatively associated with birth order, OR 0.8 (95% CI 0.7-1.0), and furry animals at home, OR 0.7 (95% CI 0.7-0.9). Incidence after age 11-12 years was associated only with family history of allergy. Multisensitization at age 19 years was significantly associated with early age at sensitization. Remission of sensitization was uncommon. CONCLUSION: The increasing prevalence of allergic sensitization by age was explained by high incidence and persistence. After age 11-12 years, the factors urban living, number of siblings, and male sex lost their importance.

Reintroduction failure is common among adolescents after double-blind placebo-controlled food challenges.

AIM: There has been a lack of research on adolescents who undergo double-blind placebo-controlled food challenges. The aim of this study was to investigate food allergic adolescents' experiences and consequences of double-blind placebo-controlled food challenges. METHODS: This qualitative, descriptive interview study included 17 adolescents aged 14-15 years with total elimination of cows' milk, hens' eggs or cod due to food allergies. The participants, who were initially identified from a large population-based cohort study, were interviewed 18 months after completing their challenges. RESULTS: The double-blind placebo-controlled food challenge proved to be a complex experience for the adolescents, involving fear of potential reactions and the hope that the food could be reintroduced. Experiences during the challenge were described in three themes: facing fears in a secure environment, being hesitant but curious about unknown tastes and waiting for unknown food reactions. Experiences after the challenge were described in two themes: gaining control and freedom and continuing old habits. A negative challenge was not consistently associated with the reintroduction of the challenged food. CONCLUSION: This study highlighted the importance of considering the adolescents' expectations and experiences of the challenge and the reintroduction process to ensure desirable changes in their dietary habits. Follow-ups should be performed regardless of the outcome of challenges.

A new quantitative PCR for human parvovirus B19 genotypes.

Parvovirus B19 (B19V) is a minute ssDNA virus associated with a wide range of diseases from childhood erythema to fetal death. After primary infection, the viral genomes persist lifelong in solid tissues of most types. Quantification of the viral DNA is important in the timing of primary infection, assessment of tissue persistence and screening of blood donor plasma. In this study, we present a new PCR assay for detection and quantification as well as for differentiation of all three B19V genotypes. A new B19V qPCR was designed to target a 154-bp region of the NS1 area. Serum, plasma and solid tissue samples were suitable for testing in the assay. The WHO International Reference Panel for Parvovirus B19 Genotypes was utilized to validate the assay for detection of different genotypes of B19V in clinical material. Each panel member yielded, by the new qPCR, a quantity similar to the one reported by National Institute for Biological Standards and Control (NIBSC). The qPCR was specific for B19V and amplified and quantified all three genotypes with detection sensitivities of ≤10 copies/reaction. The differentiation of B19V genotypes was performed by Sanger sequencing of the amplified products.

Decreased importance of environmental risk factors for childhood asthma from 1996 to 2006.

BACKGROUND: The large increase in asthma prevalence continues in several, but not all areas. Despite the individual risk factors that have been identified, the reasons for the observed trends in prevalence are largely unknown. OBJECTIVE: This study sought to characterize what trends in risk factors accompanied trends in asthma prevalence. METHODS: Two population-based cohorts of 7- to 8-year-old children from the same Swedish study areas examined by expanded International Study of Asthma and Allergy in Childhood questionnaires were compared 10 years apart. In 1996 and 2006, 3430 (97% participation) and 2585 (96% participation) questionnaires were completed, respectively. A subset was skin-prick-tested: in 1996 and 2006, 2148 (88% participation) and 1700 (90% participation) children, respectively. The adjusted population-attributable fraction (aPAF) was calculated using the prevalence and multivariate odds ratio of each risk factor. RESULTS: The prevalence of current asthma and wheeze was similar in 1996 and 2006. Allergic sensitization, however, increased from 21% to 30%. The prevalence of parental asthma increased from 17% to 24%, while respiratory infections and maternal smoking decreased (60% to 29% and 32% to 16%, respectively). The aPAFs of non-environmental risk factors for current asthma increased in 1996-2006: allergic sensitization from 35% to 41%, parental asthma from 27% to 45% and male sex from 20% to 25%. Conversely, the aPAFs of environmental risk factors decreased: respiratory infections from 36% to 32% and damp home and maternal smoking from 14% and 19%, respectively, to near zero in 2006. CONCLUSIONS AND CLINICAL RELEVANCE: From 1996 to 2006, the non-environmental risk factors parental asthma, allergic sensitization and male sex had an increasing or constant importance for current asthma in 7- to 8-year-old children. The importance of the environmental exposures damp home, respiratory infections and maternal smoking decreased. This counterbalancing in risk factors may explain the level of prevalence of current asthma.

Environmental risk factors related to the incidence of wheeze and asthma in adolescence.

BACKGROUND: Asthma is common among adolescents, but there are few population-based studies on the risk factors for incident asthma and wheeze at this age group. OBJECTIVE: To study risk factors for incident asthma and wheeze in adolescence. METHOD: Within the Obstructive Lung Disease In Northern Sweden (OLIN) studies, a cohort of 3430 school children (age 7-8 year) was recruited in 1996. In the present study, this cohort was followed from age 12-19 year. At baseline (age 12 year), 3151 participated and skin prick tests (SPT) were performed. The cohort was resurveyed annually, and risk factors for the cumulative incidence of asthma and wheeze from age 12-19 year were analysed using multivariate Cox regression. RESULTS: Female sex (wheeze: HR 1.4 95%CI 1.2-1.6; asthma: HR 1.8 95%CI 1.2-2.5) and a positive SPT to cat, dog or horse at baseline (wheeze: HR 1.6 95%CI 1.2-2.1; asthma: HR 2.3 95%CI 1.4-4.0) were significantly associated with the cumulative incidence of wheeze and asthma. Increasing numbers of siblings were inversely related to the incidence of wheeze (HR 0.9 95%CI 0.8-0.97) and asthma (HR 0.8 95%CI 0.7-0.97). Parental asthma was related to the incidence of asthma (HR 1.8 95%CI 1.2-2.6) while ever smoking (HR 2.0 95%CI 1.6-2.4) and house dampness (HR 1.3 95%CI 1.1-1.6) were risk factors for the incidence of wheeze. Maternal ETS exposure increased the risk of incident asthma in non-sensitized subjects (HR 1.9 95%CI 1.0-3.7). CONCLUSION AND CLINICAL RELEVANCE: Several environmental risk factors related to the incidence of asthma and wheeze in adolescence were identified and may be possible targets for intervention and prevention.

Hybrid simulation: bringing motivation to the art of teamwork training in the operating room.

BACKGROUND AND AIMS: Crew resource management-based operating room team training will be an evident part of future surgical training. Hybrid simulation in the operating room enables the opportunity for trainees to perform higher fidelity training of technical and non-technical skills in a realistic context. We focus on situational motivation and self-efficacy, two important factors for optimal learning in light of a prototype course for teams of residents in surgery and anesthesiology and nurses. MATERIAL AND METHODS: Authentic operating room teams consisting of residents in anesthesia (n = 2), anesthesia nurses (n = 3), residents in surgery (n = 2), and scrub nurses (n = 6) were, during a one-day course, exposed to four different scenarios. Their situational motivation was self-assessed (ranging from 1 = does not correspond at all to 7 = corresponds exactly) immediately after training, and their self-efficacy (graded from 1 to 7) before and after training. Training was performed in a mock-up operating theater equipped with a hybrid patient simulator (SimMan 3G; Laerdal) and a laparoscopic simulator (Lap Mentor Express; Simbionix). The functionality of the systematic hybrid procedure simulation scenario was evaluated by an exit questionnaire (graded from 1 = disagree entirely to 5 = agree completely). RESULTS AND CONCLUSIONS: The trainees were mostly intrinsically motivated, engaged for their own sake, and had a rather great degree of self-determination toward the training situation. Self-efficacy among the team members improved significantly from 4 to 6 (median). Overall evaluation showed very good result with a median grading of 5. We conclude that hybrid simulation is feasible and has the possibility to train an authentic operating team in order to improve individual motivation and confidence.

Mixed virtual reality simulation--taking endoscopic simulation one step further.

This pilot study aimed to assess medical students' appraisals of a "mixed" virtual reality simulation for endoscopic surgery (with a virtual patient case in addition to a virtual colonoscopy) as well as the impact of this simulation set-up on students' performance. Findings indicate that virtual patients can enhance contextualization of simulated endoscopy and thus facilitate an authentic learning environment, which is important in order to increase motivation.

Comparison of Th-cell immunity against human bocavirus and parvovirus B19: proliferation and cytokine responses are similar in magnitude but more closely interrelated with human bocavirus.

Human parvovirus B19 (B19) has been, for decades, the only parvovirus known to be pathogenic in humans. Another pathogenic human parvovirus, human bocavirus (HBoV), was recently identified in respiratory samples from children with acute lower respiratory tract symptoms. Both B19 and HBoV are transmitted by the respiratory route. The vast majority of adults are IgG seropositive for HBoV, whereas the HBoV-specific Th-cell immunity has not much been studied. The aim of this study was to increase our knowledge on HBoV-specific Th-cell immunity by examining HBoV-specific T-cell proliferation, Interferon-gamma (IFN-γ), IL-10 and IL-13 responses in 36 asymptomatic adults. Recombinant HBoV VP2 virus-like particles (VLP) were used as antigen. HBoV-specific responses were compared with those elicited by B19 VP2 VLP. Proliferation, IFN-γ and IL-10 responses with HBoV and B19 antigens among B19-seropositive subjects were statistically similar in magnitude, but the cytokine and proliferation responses were much more closely correlated in HBoV than in B19. Therefore, at the collective level, B19-specific Th-cell immunity appears to be more divergent than the HBoV-specific one.

Retention of knowledge after repeated virtual world CPR training in high school students.

We investigated the retention of knowledge and skills after repeated Virtual World MOS (VWMOS) team training of CPR in high school students. An experimental group of 9 students were compared to a control group of 7 students. Both groups initially received traditional CPR training and the experimental group also received 2 VWMOS sessions six months apart. Although we found no significant differences in general basic life support knowledge, the changes that occurred in the CPR guidelines were retained 18 months after the last Virtual World training session in the experimental group. Moreover fewer deviations from the CPR guidelines occurred.

Effects of repeated CPR training in virtual worlds on medical students' performance.

We report on a study that investigates the relationship between repeated training of teams managing a medical emergency (CPR) in a Virtual World and performance outcome measures in a group of 12 medical students. The focus of the training was on individual actions, but also on interaction and behavior in the team. Current CPR training seems to lack important team training aspects which this type of training is addressing. Although a pilot study, we found clear indications of improved performance related to reduced number of errors and an increased CPR efficiency. This type of educational technology could be expanded to other groups for a similar purpose because of its easiness to use, adaptability and interactivity.

The Obstructive Lung Disease in Northern Sweden (OLIN) longitudinal paediatric study I--the first 10 years.

BACKGROUND: Prospective studies of asthma and allergic conditions based on the general population are scarce. AIM: To summarize the methods and main results from a prospective study among school children. METHODS: In 1996, a cohort of 3525 children aged 7/8 years in Northern Sweden were invited to a questionnaire survey using an expanded ISAAC protocol, and 97% participated. The cohort has been followed up yearly with high participation rate. Skin prick tests were conducted 1996, 2000 and 2006/2007. Allergens in dust from homes and schools have been analyzed. Sub samples have participated in interviews, lung function tests, bronchial hyper reactivity test, and analyses of IgE and IgG antibodies in serum. RESULTS: The prevalence of asthma was 6% at age 7-8 years and increased by age. The incidence of physician-diagnosed asthma after the age of 7-8 years was around 1/100/year. The prevalence of positive skin prick test increased from 21% at age 7-8 to 30% at age 11-12 years. Remission of allergic sensitization was rare, while asthma remission was 5% yearly. The main risk factor for asthma and allergic sensitization increased in importance with increasing age. Allergic and non-allergic asthma had different risk factor pattern. Environmental risk factors decreased in impact after the age of 7. Avoidance of pets at home did not protect from asthma or allergic sensitization. CONCLUSION: The study includes important sources of data for further longitudinal analyses that will contribute to the understanding of the development and the nature of asthma and allergic sensitization.

Frequency of recent parvovirus infection in patients examined for acute reactive arthritis. A study with combinatorial parvovirus serodiagnostics.

OBJECTIVE: To determine the causative role of human parvovirus B19 as a preceding infection in patients examined for acute reactive arthritis (ReA). METHODS: Sixty adult patients with acute arthritis were screened for evidence of triggering infections. In all patients, cultures of stool specimens and of Chlamydia trachomatis in urethra/cervix, and/or bacterial serology were studied. The timing of primary infection of human parvovirus B19 was determined by measurement in serum of VP2-IgM, VP2-IgG, epitope-type specifity of VP2-IgG, and avidity of VP1-IgG. RESULTS: Median time from onset of joint symptoms to the rheumatological consultation was five weeks (range 1-62). Of the 60 patients, 35 fulfilled the diagnostic criteria for ReA; in the remaining, the diagnosis was unspecified arthritis (UA). Thirty-six patients had antibodies for the B19 virus. Occurrence of these antibodies did not differ significantly between ReA and UA groups (P = 0.61). Of these 36 patients, 34 had a pre-existing immunity to the B19 virus. Of the two other patients, one had rash and self-limiting polyarthritis with serological evidence of B19 primary infection, and the other had arthritis of the lower extremities with serological evidence of a convalescence period after the B19 primary infection. The latter patient also had antibodies to Yersinia, with a clinical picture typical for ReA. CONCLUSION: In patients examined for acute ReA, the frequency of recent B19 virus infection was 3.3% (2 out of 60). The diagnostic utility of the presented methodology, by using a single serum sample, was evident.

Visual working memory influences the performance in virtual image-guided surgical intervention.

BACKGROUND: This study addresses for the first time the relationship between working memory and performance measures in image-guided instrument navigation with Minimally Invasive Surgical Trainer-Virtual Reality (MIST-VR) and GI Mentor II (a simulator for gastroendoscopy). In light of recent research on simulator training, it is now prime time to ask why in a search for mechanisms rather than show repeatedly that conventional curriculum for simulation training has effect. METHODS: The participants in this study were 28 Swedish medical students taking their course in basic surgery. Visual and verbal working memory span scores were assessed by a validated computer program (RoboMemo) and correlated with visual-spatial ability (MRT-A test), total flow experience (flow scale), mental strain (Borg scale), and performance scores in manipulation and diathermy (MD) using Procedicus MIST-VR and GI Mentor 11 (exercises 1 and 3). RESULTS: Significant Pearson's r correlations were obtained between visual working memory span scores for visual data link (a RoboMemo exercise) and movement economy (r = -0.417; p < 0.05), total time (r = -0.495; p < 0.01), and total score (r = -0.390; p < 0.05) using MIST-MD, as well as total time (r = -0.493; p < 0.05) and efficiency of screening (r = 0.469; p < 0.05) using GI Mentor 11 (exercise 1). Correlations also were found between visual working memory span scores in rotating data link (another RoboMemo exercise) and both total time (r = -0.467; p < 0.05) and efficiency of screening (r = -0.436; p < 0.05) using GI Mentor 11 (exercise 3). Significant Pearson's r correlations also were found between visual-spatial ability scores and several performance scores for the MIST and GI Mentor II exercises. CONCLUSIONS: Findings for the first time demonstrate that visual working memory for surgical novices may be important for performance in virtual simulator training with two well-known and validated simulators.

Visual-spatial ability and interpretation of three-dimensional information in radiographs.

OBJECTIVES: To investigate whether skill in the interpretation of three-dimensional (3D) information in radiographs utilizing the parallax phenomenon is associated with visual-spatial ability and whether development of this skill is related to visual-spatial ability. METHODS: Eighty-six individuals with a median age of 25 years participated in the study. It was organized into three parts: (1) assessment before training, (2) training in object depth localization utilizing parallax and (3) assessment after training. Before training, visual-spatial ability was assessed with a mental rotation test, MRT-A; skill in interpreting 3D information was assessed with two specifically designed proficiency tests: a radiography test, which assessed the ability to interpret 3D information in radiographs utilizing motion parallax and a principle test which assessed understanding of the principles of motion parallax. After training, skill in interpreting 3D information was reassessed. Improvement was defined as the difference between test scores after training and before training. Multiple linear regression was used to analyse the effect of student and training characteristics on proficiency test results and improvement. RESULTS: Radiography test results after training and improvement of radiography test results were significantly associated with MRT-A scores (P<0.001 and P=0.020, respectively). Principle test results were high before training and did not improve after training. The test results were associated with MRT-A both before (P=0.009) and after training (P=0.003). CONCLUSIONS: Understanding of the parallax phenomenon is associated with visual-spatial ability. Development of the skill to interpret 3D information in radiographs utilizing parallax is facilitated for individuals with high visual-spatial ability.

Implementing virtual worlds for systematic training of prehospital CPR in medical school.

We report on a study that investigates the relationship between repeated training of teams managing medical emergencies in the Virtual World and affective learning outcomes in a group of 12 medical students. The focus of the training was on individual actions, but also on interaction and behaviour in the team. Current CPR training seems to lack important team training aspects which this type of training is addressing. We found an increase in flow experience and in self efficacy. This type of training could probably be expanded to other groups for a similar purpose because of its easiness to use, adaptability and interactivity.

High-level visual-spatial ability for novices correlates with performance in a visual-spatial complex surgical simulator task.

BACKGROUND: This study addresses how high-level visual-spatial ability of surgical novices is related to performance of two simulator tasks with (KSA) and without (MIST) anatomic graphics and haptic feedback, differing in visual-spatial complexity. METHODS: Visual-spatial test scores assessed by Mental Rotation Test (MRT) and BasIQ and performance scores for Instrument Navigation (IN) in Key Surgical Activities (Procedicus KSA) and Manipulate and Diathermy (MD) in Minimally Invasive Surgical Trainer (Procedicus MIST) were correlated for 54 Swedish surgical novices. RESULTS: Significant Pearson's r correlations were obtained between visual-spatial scores measured by MRT-C and total score from the last trial for IN (r = 0.278, p < 0.05). Visual-spatial scores (measured by BasIQ) also correlated with total score from the first trial (r = 0.443, p < 0.05) and from the last trial (r = 0.489, p < 0.05). CONCLUSION: High-level visual-spatial ability is important for surgical novices to possess in the early training phase of a visual-spatial complex task in KSA.

Early exposure to haptic feedback enhances performance in surgical simulator training: a prospective randomized crossover study in surgical residents.

BACKGROUND: In the literature of skill acquisition and transfer of skills, it often is assumed that the rate of skill acquisition depends on what has been learned in a similar context (i.e., surgical simulators providing haptic feedback). This study aimed to analyze whether the addition of haptic feedback early in the training phase for image-guided surgical simulation improves performance. METHODS: A randomized crossover study design was used, in which 38 surgical residents were randomized to begin a 2-h simulator training session with either haptic or nonhaptic training followed by crossover after 1 h. The graphic context was a virtual upper abdomen. The residents performed two diathermy tasks. Two validated tests were used to control for differences in visual-spatial ability: the BasIQ general cognitive ability test and Mental Rotation Test A (MRT-A). RESULTS: After 2 h of training, the group that had started with haptic feedback performed the two diathermy tasks significantly better (p < 0.05, unpaired t-test). Only the group that had started with haptic training significantly improved during the last 1-h session (p < 0.01, paired t-test). CONCLUSION: The findings indicate that haptic feedback could be important in the early training phase of skill acquisition in image-guided surgical simulator training.

Objective assessment of visuospatial and psychomotor ability and flow of residents and senior endoscopists in simulated gastroscopy.

BACKGROUND: Advanced medical simulators have predominantly been used to shorten the learning curve of endoscopy for medical students and young residents. Rarely have the effects of visuospatial ability and attitudes of intermediately experienced and experienced specialists been studied with regard to simulator training. The aim of this study was to assess the effects of visuospatial ability and attitude on performance in simulator training. METHODS: Eighteen surgical residents were included in the study. Prior to the simulated gastroscopy task, they performed a visuospatial test (the card rotation test). After the simulated gastroscopy task, they completed a questionnaire regarding flow experiences. Their results were compared with those of 11 expert endoscopists who performed the same tests. RESULTS: Total gastroscopy time was significantly shorter for the expert endoscopists compared to residents (2 min 11 sec, p = 0.003). There was also a trend of more mucosa inspected (p = 0.088) and higher efficiency of screening (p = 0.069) by the experts. The residents made fewer errors in the card rotation test than the expert endoscopists (2.5 +/- 0.8 vs 5.5 +/- 1.2, respectively; p = 0.034), and their visuospatial card rotation test results correlated better with their performance in the simulated gastroscopy. CONCLUSIONS: A virtual gastroscopy task presents more of an emotional as well as a psychomotoric challenge to intermediately experienced endoscopists than to senior experts. Our study demonstrates that these differences can be objectively assessed by the use of visuospatial ability tests, flowsheets, and an endoscopic simulator.

Delayed maturation of IgG avidity in congenital toxoplasmosis.

The aim of this comparative study was to investigate the clinical usefulness of the measurement of Toxoplasma gondii IgG avidity in the postnatal diagnosis of congenital toxoplasmosis. IgG avidity values in serum samples from infants with congenital infection were compared with those in samples from uninfected infants, all born to mothers with toxoplasmosis acquired during gestation. This analysis revealed that IgG avidity values soon after birth reflected maternal values in the large majority of the samples. Low or borderline IgG avidity values were systematically found in the cohort of congenitally infected subjects. After birth, IgG avidity values slowly increased over time for up to 2 years in congenitally infected subjects. On the contrary, IgG avidity values in the uninfected infants remained stable over time. The presence of low IgG avidity in a newborn can be considered a marker of maternal seroconversion in the second or third trimester of gestation and, as a consequence, an indicator of risk for congenital toxoplasmosis. An IgG avidity assay can be easily carried out with antibodies eluted from dried blood spots (Guthrie cards), providing an opportunity to retrospectively evaluate the risk of congenital infection in special clinical circumstances, for example when suspicion of congenital infection arises during late infancy.