Impact of comorbidity on disease characteristics, treatment intent and outcome in diffuse large B-cell lymphoma: a Swedish lymphoma register study

BACKGROUND

Comorbidity impacts overall survival amongst patients with diffuse large B-cell lymphoma (DLBCL). However, associations of comorbidity with lymphoma characteristics, treatment selection and lymphoma-specific mortality are less well known.

OBJECTIVE

To examine the impact of comorbidity on DLBCL characteristics, treatment intent and cause of death.

METHODS

We identified 3905 adult patients diagnosed with DLBCL 2007-2013 through the Swedish Lymphoma Register. We assessed comorbid disease history according to the Charlson comorbidity index (CCI). Comorbidity data and causes of death were collected through register linkage. Associations were estimated using multinomial regression and flexible parametric survival models.

RESULTS

Overall, 45% of the patients (n = 1737) had a history of at least one comorbidity at DLBCL diagnosis (cardiovascular disease, diabetes and solid cancer were most frequent), and 997 (26%) had a CCI score of ≥2. The relative probability of presenting with poor performance status (PS > 2) was higher amongst comorbid patients [Relative Risk Ratio (RRR)_PS>2 : 2.02, 95% CI: 1.63-2.51]. Comorbid patients had a substantially lower relative probability of receiving curative treatment (RRR: 0.48, 95% CI: 0.38-0.61). Amongst all patients, CCI ≥ 1 was associated with a significantly increased risk of all-cause and lymphoma-specific death after adjustments. Amongst patients selected for curative treatment, comorbidity was associated with an increased risk of all-cause death (HR_CCI>1 : 1.54, 95% CI: 1.32-1.80), but not with lymphoma-specific death (HR_CCI>1 : 1.05, 95% CI: 0.86-1.28).

CONCLUSION

Comorbidity is associated with inferior DLBCL outcome, mainly due to a lower likelihood of receiving treatment with curative intent. Possibly, more comorbid DLBCL patients could be treated with curative intent if comorbid conditions were optimized in parallel.

Down-regulation of the inflammatory response after short-term exposure to low levels of chemical vapours

OBJECTIVE

To investigate the relation between signs and symptoms of irritation and biomarkers of inflammatory markers in blood in healthy volunteers exposed to different chemical vapours for 2 or 4 hours in an exposure chamber.

METHODS

The investigated chemicals were: acetic acid (5 and 10 ppm), acrolein (0.05 and 0.1 ppm), 1,4-dioxane (20 ppm), n-hexanal (2 and 10 ppm), hydrogen peroxide (0.5 and 2.2 ppm), 2-propanol (150 ppm), m-xylene (50 ppm), standard and dearomatised white spirit (100 and 300 mg/m³). C reactive protein (CRP), serum amyloid A protein and interleukin 6 were measured in plasma immediately before and 2 or 4 hours after the exposures. Symptoms were rated from 0 to 100 mm in Visual Analogue Scales and covered 10 questions whereof four related to irritation: discomfort in the eyes, nose and throat and dyspnoea. The effect measurements included blink frequency by electromyography, nasal swelling by acoustic rhinometry and lung function by spirometry.

RESULTS

Logistic quantile regression analyses revealed no significant associations except a negative relation between ratings of irritation and CRP.

CONCLUSION

The results suggest a down-regulation of CRP after short-term exposure to low levels of vapours of irritating chemicals. This response might be mediated by the cholinergic anti-inflammatory pathway and further studies are recommended in order to refute or confirm this hypothesis.

A penalized approach to covariate selection through quantile regression coefficient models

The coefficients of a quantile regression model are one-to-one functions of the order of the quantile. In standard quantile regression (QR), different quantiles are estimated one at a time. Another possibility is to model the coefficient functions parametrically, an approach that is referred to as quantile regression coefficients modeling (QRCM). Compared with standard QR, the QRCM approach facilitates estimation, inference and interpretation of the results, and generates more efficient estimators. We designed a penalized method that can address the selection of covariates in this particular modelling framework. Unlike standard penalized quantile regression estimators, in which model selection is quantile-specific, our approach permits using information on all quantiles simultaneously. We describe the estimator, provide simulation results and analyse the data that motivated the present article. The proposed approach is implemented in the qrcmNP package in R.

Mesenchymal stromal cells modulate tissue repair responses within the injured vocal fold

OBJECTIVES/HYPOTHESIS

This study aimed to determine whether local injection of human mesenchymal stromal cells (MSC) could modulate the early inflammatory response within injured vocal folds (VFs) to promote wound-healing processes.

STUDY DESIGN

Experimental xenograft model.

METHODS

VF injury was surgically induced by bilateral resection of the lamina propria of rabbits, and MSC were immediately injected into the injured area of both VFs. Animals were sacrificed on days 2, 4, and 24. Histological analyses were performed by hematoxylin and eosin, Masson's Trichrome, and elastin staining. Cell death was visualized by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), and the M2 macrophage marker, CD163, detected by immunohistochemistry. Persistence of injected MSC was evaluated by fluorescent in situ hybridization (FISH). Quantitative polymerase chain reaction was performed on the contralateral VF.

RESULTS

Histological examination at days 2 and 4 indicated that MSC were able to reduce tissue inflammation, with gene expression analysis confirming a significant reduction of proinflammatory markers, interleukin (IL)-1β, and IL-8. FISH demonstrated low-level persistence of injected MSC at both time points, and TUNEL confirmed localized cell death at the injury site. Increased levels of CD163+ anti-inflammatory macrophages indicated a change in the immune milieu, supporting wound resolution. Evidence of a more organized collagen matrix suggests that MSC may enhance the production of a functional repair tissue after injury, despite their low-level persistence within the tissue.

CONCLUSIONS

This study demonstrates that MSC are able to positively modulate the early wound-healing response through resolution of the inflammatory phase and promotion of tissue repair.

LEVEL OF EVIDENCE

NA Laryngoscope, 130:E21-E29, 2020.

Body mass index in early pregnancy and future risk of severe liver disease: a population-based cohort study

BACKGROUND

In young men, high body mass index (BMI) has been linked to liver disease later in life, but it is unclear if this also applies to women.

AIM

To study the association between BMI early in life and development of liver disease later in life in women.

METHODS

We obtained data on early pregnancy BMI from 1 139 458 Swedish women between 1992 and 2015. National registers were used to ascertain incident severe liver disease, defined as cirrhosis, decompensated liver disease (hepatocellular carcinoma, oesophageal varices, hepatorenal syndrome or hepatic encephalopathy) or liver failure. A Cox regression model was used to investigate associations of BMI with incident severe liver disease adjusting for maternal age, calendar year, country of birth, smoking, civil status and education.

RESULTS

During an average follow-up of 13.8 years, 774 women developed severe liver disease. Compared to women with a low normal BMI (18.5-22.4), an increased risk of severe liver disease was found in women with BMI between 22.5 and 24.9 kg/m² (adjusted hazard ratio [aHR] 1.25, 95% CI 1.04-1.50), 25.0 and 29.9 kg/m² (aHR 1.27, 95% CI 1.05-1.53) and BMI ≥ 30 kg/m² (aHR 1.77, 95% CI 1.40-2.24). When examining BMI as a continuous variable, the aHR increased by 4% per kg/m² (95% CI 1.02-1.05). A diagnosis of diabetes was associated with an increased risk of severe liver disease independent of baseline BMI.

CONCLUSION

A high BMI early in life in women is associated with a dose-dependent, increased risk for future severe liver disease.

Comparison of Frequentist and Bayesian Generalized Additive Models for Assessing the Association Between Daily Exposure to Fine Particles and Respiratory Mortality: A Simulation Study

Objective: To compare the performance of frequentist and Bayesian generalized additive models (GAMs) in terms of accuracy and precision for assessing the association between daily exposure to fine particles and respiratory mortality using simulated data based on a real time-series study. Methods: In our study, we examined the estimates from a fully Bayesian GAM using simulated data based on a genuine time-series study on fine particles with a diameter of 2.5 μm or less (PM_2.5) and respiratory deaths conducted in Shanghai, China. The simulation was performed by multiplying the observed daily death with a random error. The underlying priors for Bayesian analysis are estimated using the real world time-series data. We also examined the sensitivity of Bayesian GAM to the choice of priors and to true parameter. Results: The frequentist GAM and Bayesian GAM show similar means and variances of the estimates of the parameters of interest. However, the estimates from Bayesian GAM show relatively more fluctuation, which to some extent reflects the uncertainty inherent in Bayesian estimation. Conclusions: Although computationally intensive, Bayesian GAM would be a better solution to avoid potentially over-confident inferences. With the increasing computing power of computers and statistical packages available, fully Bayesian methods for decision making may become more widely applied in the future.

Traffic noise exposure in relation to adverse birth outcomes and body mass between birth and adolescence

BACKGROUND

There is growing evidence that traffic noise exposure is associated with adiposity among adults but data in children are limited.

OBJECTIVE

This longitudinal study examined whether pre- and postnatal noise exposure is associated with body mass index (BMI) between birth and adolescence or with adverse birth outcomes.

METHODS

The study was conducted using data from the BAMSE birth cohort, which included 4089 children born in Stockholm County, Sweden. Data on BMI from birth to adolescence were collected via questionnaires, clinical examinations and health care records. A national register provided information on birth outcomes. Road traffic noise levels at the most exposed façade were estimated for all residences of the children during follow-up, as well as of their mothers during pregnancy, and time-weighted average exposure was calculated for different time windows. Maternal occupational noise exposure was obtained from a job-exposure-matrix. Logistic- and quantile regression models were used to estimate associations between noise exposure and health outcomes.

RESULTS

We found residential road traffic noise exposure to be associated with increases in BMI from school age to adolescence, but not at earlier ages. In the age groups 8-11 years and 12-16 years the BMI increments were 0.11 kg/m² per 10 dB L_den (95% CI 0.08-0.13) and 0.20 kg/m² per 10 dB L_den (95% CI 0.17-0.22), respectively. Maternal noise exposure during pregnancy was generally unrelated to adverse birth outcomes and BMI from birth to adolescence in the children, however, traffic noise exposure was associated with a decreased risk of preterm birth CONCLUSION: Residential road traffic noise exposure was associated with BMI increases from school age to adolescence, but not at earlier ages. Maternal occupational noise exposure or exposure from road traffic during pregnancy were not consistently related to birth outcomes or BMI from birth to adolescence.

Are you suffering from a large arterial occlusion? Please raise your arm!

Background and purpose

Triage tools to identify candidates for thrombectomy are of utmost importance in acute stroke. No prognostic tool has yet gained any widespread use. We compared the predictive value of various models based on National Institutes of Health Stroke Scale (NIHSS) subitems, ranging from simple to more complex models, for predicting large artery occlusion (LAO) in anterior circulation stroke.

Methods

Patients registered in the SITS international Stroke Register with available NIHSS and radiological arterial occlusion data were analysed. We compared 2042 patients harbouring an LAO with 2881 patients having no/distal occlusions. Using binary logistic regression, we developed models ranging from simple 1 NIHSS-subitem to full NIHSS-subitems models. Sensitivities and specificities of the models for predicting LAO were examined.

Results

The model with highest predictive value included all NIHSS subitems for predicting LAO (area under the curve (AUC) 0.77), yielding a sensitivity and specificity of 69% and 76%, respectively. The second most predictive model (AUC 0.76) included 4-NIHSS-subitems (level of consciousness commands, gaze, facial and arm motor function) yielding a sensitivity and specificity of 67% and 75%, respectively. The simplest model included only deficits in arm motor-function (AUC 0.72) for predicting LAO, yielding a sensitivity and specificity of 67% and 72%, respectively.

Conclusions

Although increasingly more complex models yield a higher discriminative performance for predicting LAO, differences between models are not large. Assessing grade of arm dysfunction along with an established stroke-diagnosis model may serve as a surrogate measure of arterial occlusion-status, thereby assisting in triage decisions.

Optimal probability weights for estimating causal effects of time-varying treatments with marginal structural Cox models

Marginal structural Cox models have been used to estimate the causal effect of a time-varying treatment on a survival outcome in the presence of time-dependent confounders. These methods rely on the positivity assumption, which states that the propensity scores are bounded away from zero and one. Practical violations of this assumption are common in longitudinal studies, resulting in extreme weights that may yield erroneous inferences. Truncation, which consists of replacing outlying weights with less extreme ones, is the most common approach to control for extreme weights to date. While truncation reduces the variability in the weights and the consequent sampling variability of the estimator, it can also introduce bias. Instead of truncated weights, we propose using optimal probability weights, defined as those that have a specified variance and the smallest Euclidean distance from the original, untruncated weights. The set of optimal weights is obtained by solving a constrained quadratic optimization problem. The proposed weights are evaluated in a simulation study and applied to the assessment of the effect of treatment on time to death among people in Sweden who live with human immunodeficiency virus and inject drugs.

Development of an ICU discharge instrument predicting psychological morbidity: a multinational study

Purpose

To develop an instrument for use at ICU discharge for prediction of psychological problems in ICU survivors.

Methods

Multinational, prospective cohort study in ten general ICUs in secondary and tertiary care hospitals in Sweden, Denmark and the Netherlands. Adult patients with an ICU stay ≥ 12 h were eligible for inclusion. Patients in need of neurointensive care, with documented cognitive impairment, unable to communicate in the local language, without a home address or with more than one limitation of therapy were excluded. Primary outcome was psychological morbidity 3 months after ICU discharge, defined as Hospital Anxiety and Depression Scale (HADS) subscale score ≥ 11 or Post-traumatic Stress Symptoms Checklist-14 (PTSS-14) part B score > 45.

Results

A total of 572 patients were included and 78% of patients alive at follow-up responded to questionnaires. Twenty percent were classified as having psychological problems post-ICU. Of 18 potential risk factors, four were included in the final prediction model after multivariable logistic regression analysis: symptoms of depression [odds ratio (OR) 1.29, 95% confidence interval (CI) 1.10–1.50], traumatic memories (OR 1.44, 95% CI 1.13–1.82), lack of social support (OR 3.28, 95% CI 1.47–7.32) and age (age-dependent OR, peak risk at age 49–65 years). The area under the receiver operating characteristics curve (AUC) for the instrument was 0.76 (95% CI 0.70–0.81).

Conclusions

We developed an instrument to predict individual patients’ risk for psychological problems 3 months post-ICU, http://www.imm.ki.se/biostatistics/calculators/psychmorb/. The instrument can be used for triage of patients for psychological ICU follow-up.

Trial registration

The study was registered at clinicaltrials.gov, NCT02679157.

Electronic supplementary material

The online version of this article (10.1007/s00134-018-5467-3) contains supplementary material, which is available to authorized users.

Extracellular microvesicle microRNAs as predictive biomarkers for targeted therapy in metastastic cutaneous malignant melanoma

BACKGROUND

Mitogen activated-protein kinase pathway inhibitors (MAPKis) improve treatment outcome in patients with disseminated BRAFV600 mutant cutaneous malignant melanoma (CMM) but responses are of limited duration due to emerging resistance. Although extensive research in mechanisms of resistance is being performed, predictive biomarkers for durable responses are still lacking. We used miRNA qPCR to investigate if different levels of extracellular microvesicle microRNA (EV miRNA) in matched plasma samples collected from patients with metastatic IV BRAFV600 mutated CMM before, during and after therapy with MAPKis could serve as predictive biomarkers.

MATERIALS AND METHODS

EV miRNAs were extracted from plasma samples from 28 patients collected before and during therapy, measured by quantitative PCR-array and correlated to therapy outcome.

RESULTS

Increased levels of EV let-7g-5p during treatment compared to before treatment (EV let-7g-5p_delta) were associated with better disease control with MAPKis (odds ratio 8568.4, 95% CI = 4.8-1.5e+07, P = 0.000036). Elevated levels of EV miR-497-5p during therapy were associated with prolonged progression free survival (PFS) (hazard ratio = 0.27, 95% CI = 0.13-0.52, P <0.000061).

CONCLUSIONS

EV miRNAs let-7g-5p and miR-497-5p were identified as putative novel predictive biomarkers of MAPKi treatment benefit in metastatic CMM patients highlighting the potential relevance of assessing EV miRNA during and after treatment to unravel novel mechanisms of resistance.

Marginal quantile regression for dependent data with a working odds-ratio matrix

Dependent data arise frequently in applied research and several approaches to adjusting for the dependence among observations have been proposed in quantile regression. Cluster bootstrap is generally inefficient and computationally demanding, especially when the number of clusters is large. When the primary interest is on marginal quantiles, estimating equations have been proposed that estimate a working correlation matrix from the regression residuals' sign. However, the Pearson's correlation coefficient is an inadequate measure of dependence between binary variables because its range depends on their marginal probabilities. Instead, we propose to model the working correlation matrix through odds ratios. Different working structures can be easily estimated by suitable logistic regression models. These structures can be parametrized to depend on covariates and clusters. Simulations show that the proposed estimator has similar behavior to that of generalized estimating equations applied to regression for the mean. We study marginal quantiles of cognitive behavior with data from a randomized trial for treatment of obsessive compulsive disorder.

Assessing the degree of residual confounding: a cohort study on the association between disability pension and mortality

Background

Previous studies showed that disability pensioners have a higher risk of premature death than others, but residual confounding has been suggested. The aim was to assess the degree of residual confounding of the association between disability pension (DP) and risk of premature death.

Methods

Prospective cohort study of everyone aged 19-64 years, living in Sweden 31 December 2004 (n = 5 406 469), followed up through 2010. Mortality hazard rates over time were estimated for three groups; incident disability pensioners during 2005 from start of DP (February-December 2005), prevalent disability pensioners (January 2005 or since before), and individuals not on DP in January 2005, after standardizing populations to characteristics of the incident disability pensioners, stratified by previous hospitalization or not. If DP has no immediate effect on mortality, incident disability pensioners and those not on DP should initially have similar hazard rates, thereby, allowing assessment of the degree of residual confounding.

Results

For those not previously hospitalized, the mortality hazard rate on the first DP day was: 3.07 (95% CI 2.21, 4.36), 2.09 (1.78, 2.48) and 0.78 (0.73, 0.84) per thousand person-years for incident, prevalent, and non DP, respectively. Among previously hospitalized these figures were: 21.67 (17.73, 26.24), 17.00 (15.76, 18.51) and 18.88 (18.14, 19.64) respectively. Hazard ratios were 1.15 (0.94, 1.40) in the strata with and 3.94 (2.78, 5.57) in the strata without, previous hospitalization comparing incident DP with non-DP.

Conclusions

Substantial residual confounding was found in the association between DP and premature death among those not previously hospitalized.

Effect of radiotherapy for rectal cancer on ovarian androgen production

Background

The impact of radiotherapy (RT) for rectal cancer on ovarian androgen production is unknown. The aim was to examine the effect of RT for rectal cancer on androgen levels in non-oophorectomized women and the association with female sexual desire.

Methods

This prospective cohort study included women who had surgery for rectal cancer with or without RT. Serum testosterone, free testosterone, androstenedione and dehydroepiandrosterone sulphate (DHEA-S) levels were assessed at baseline, after RT and 1 year after surgery. Sexual desire was assessed by means of the Female Sexual Function Index.

Results

Twenty-seven participants had surgery alone (RT– group) and 98 had preoperative RT and surgery (RT+ group). During the first year after surgery, median serum testosterone and free testosterone levels decreased from 0·6 (range 0·1–3·6) to 0·5 (0·1–2·3) nmol/l (P &lt; 0·001) and from 9·1 (1·6–45·8) to 7·9 (1·4–22·7) pmol/l (P &lt; 0·001) respectively in the RT+ group, but did not change in the RT– group. Longitudinal regression analysis confirmed a decrease in testosterone and free testosterone after RT. The adjusted change in androstenedione and DHEA-S was not significant in any group. The mean change in testosterone (odds ratio (OR) 2·74, 95 per cent c.i. 1·06 to 7·11; P = 0·038), free testosterone (OR 1·08, 1·02 to 1·15; P = 0·011), androstenedione (OR 1·52, 1·07 to 2·16; P = 0·019) and DHEA-S (OR 0·49, 0·27 to 0·89; P = 0·019) was related to change in sexual desire.

Conclusion

RT decreased levels of androgens predominantly derived from the ovaries, whereas androgens of mainly adrenal origin remained unchanged. Reduction in ovarian androgens may be associated with reduced sexual desire.

Study protocol for a single-blind, randomised controlled, non-inferiority trial of internet-based versus face-to-face cognitive behaviour therapy for obsessive-compulsive disorder

INTRODUCTION

Expert guidelines recommend cognitive-behavioural therapy (CBT) as a first-line treatment for obsessive-compulsive disorder (OCD), but the majority of patients with OCD do not have access to CBT. Internet-delivered CBT (ICBT) has the potential to make this evidence-based treatment more accessible while requiring less therapist time than traditional face-to-face (f2f) CBT. Data from six clinical trials suggest that ICBT for OCD is both efficacious and cost-effective, but whether ICBT is non-inferior to traditional f2f CBT for OCD is yet unknown.

METHODS AND ANALYSIS

A single-blind, randomised, controlled, non-inferiority trial comparing therapist-guided ICBT, unguided ICBT and individual (f2f) CBT for adult OCD patients. The primary objective is to investigate whether ICBT is non-inferior to gold standard f2f CBT. Secondary objectives are to investigate if ICBT is equally effective when delivered unguided, to establish the cost-effectiveness of ICBT and to investigate if the treatment outcome differs between self-referred and clinically referred patients. Participants will be recruited at two specialist OCD clinics in Stockholm and also through online self-referral. Participants will be randomised to one of three treatment conditions: F2f CBT, ICBT with therapist support or unguided ICBT. The total number of participants will be 120, and masked assessments will be administered at baseline, biweekly during treatment, at post-treatment and at 3-month and 12-month follow-ups. The main outcome measure is the clinician-rated Yale-Brown Obsessive Compulsive Scale (Y-BOCS) at 3-month follow-up. The margin of non-inferiority is set to 3 points on the Y-BOCS using a 90% CI.

ETHICS AND DISSEMINATION

The study has been approved by the Regional Ethics Board of Stockholm (REPN 2015/1099-31/2) and registered at Clinicaltrials.gov (NCT02541968). The study will be reported in accordance with the Consolidated Standards of Reporting Trials statement for non-pharmacological trials. The results will be published in peer-reviewed academic journals and disseminated to patient organisations and media.

TRIAL REGISTRATION NUMBER

NCT02541968; Pre-results.

Neglected exposure route: cobalt on skin and its associations with urinary cobalt levels

OBJECTIVES

Cobalt (Co) exposure is associated with adverse health effects including skin sensitisation, asthma and interstitial lung fibrosis. Exposure to Co in industrial settings is often assessed using air samples or biomonitoring in urine. Skin exposure is rarely measured. Aim of this study was to quantify and compare the importance of Co skin exposure and respiratory exposure in determining urinary Co concentrations.

METHODS

Co skin exposure was measured in 76 hard metal workers by acid wipe sampling before and at the end of work shifts. Spot urine was collected during a 24-hour period from the start of a shift. Respiratory exposure was measured by personal inhalable dust sampling during a shift in 30 workers. Co was analysed by inductively coupled plasma mass spectrometry.

RESULTS

Quantile regression modelling showed that a doubling of Co on skin before or at the end of shift increased the median urinary concentration of Co by 70% (p<0.001) or 32% (p<0.001), respectively. A doubling of Co in air increased median urinary Co by 38% (p<0.001). Co skin exposures were still significantly associated with urinary Co after excluding a group of workers with high respiratory exposure (33%, p=0.021 and 17%, p=0.002).

CONCLUSIONS

The results indicate an association between Co skin exposure and urinary Co concentrations. This should be considered when using urinary Co as a biomarker of exposure.

Restorative surgery after colectomy for ulcerative colitis in England and Sweden: observations from a comparison of nationwide cohorts

AIM

A longstanding disparity exists between the approaches to restorative surgery after colectomy for patients with ulcerative colitis (UC) in England and Sweden. This study aims to compare rates of colectomy and restorative surgery in comparable national cohorts.

METHOD

The English Hospital Episode Statistics (HES) and Swedish National Patient Register (NPR) were interrogated between 2002 and April 2012. Patients with two diagnostic episodes for UC (age ≥ 15 years) were included. Patients were excluded if they had an episode of inflammatory bowel disease or colectomy before 2002. The cumulative incidences of colectomy and restorative surgery were calculated using the Kaplan-Meier method.

RESULTS

A total of 98 691 patients were included in the study, 76 129 in England and 22 562 in Sweden. The 5-year cumulative incidence of all restorative surgery after colectomy in England was 33% vs 46% in Sweden (P-value < 0.001). Of the patients undergoing restorative surgery, 92.3% of English patients had a pouch vs 38.8% in Sweden and 7.7% vs 59.1% respectively had an ileorectal anastomosis (IRA). The 5-year cumulative incidence of colectomy in this study cohort was 13% in England and 6% in Sweden (P-value < 0.001).

CONCLUSION

Following colectomy for UC only one-third of English patients and half of Swedish patients underwent restorative surgery. In England nearly all these patients underwent pouches, in Sweden a less significant majority underwent IRAs. It is surprising to demonstrate this discrepancy in a comparable cohort of patients from similar healthcare systems. The causes and consequences of this international variation in management are not fully understood and require further investigation.

One-stage dose-response meta-analysis for aggregated data

The standard two-stage approach for estimating non-linear dose-response curves based on aggregated data typically excludes those studies with less than three exposure groups. We develop the one-stage method as a linear mixed model and present the main aspects of the methodology, including model specification, estimation, testing, prediction, goodness-of-fit, model comparison, and quantification of between-studies heterogeneity. Using both fictitious and real data from a published meta-analysis, we illustrated the main features of the proposed methodology and compared it to a traditional two-stage analysis. In a one-stage approach, the pooled curve and estimates of the between-studies heterogeneity are based on the whole set of studies without any exclusion. Thus, even complex curves (splines, spike at zero exposure) defined by several parameters can be estimated. We showed how the one-stage method may facilitate several applications, in particular quantification of heterogeneity over the exposure range, prediction of marginal and conditional curves, and comparison of alternative models. The one-stage method for meta-analysis of non-linear curves is implemented in the dosresmeta R package. It is particularly suited for dose-response meta-analyses of aggregated where the complexity of the research question is better addressed by including all the studies.

Early life determinants of lung function change from childhood to adolescence

RATIONALE

Little is known about how perinatal and childhood factors influence lung function change between childhood and adolescence.

OBJECTIVES

To investigate possible early life predictors of change in FEV₁ between age 8 and 16 years. In addition, to investigate possible predictors of having persistently low lung function (FEV₁ <25th percentiles both at age 8 and 16) up to adolescence.

METHODS

The BAMSE birth cohort study collected data throughout childhood on environmental factors, individual characteristics, and spirometric measures at 8 and 16 years (n = 1425). Associations between early life predictors (n = 31) and FEV₁ increase between 8 and 16 years were assessed with linear regression. Predictors of having persistently low lung function were examined.

RESULTS

Few factors were consistently associated with altered lung function growth, although low birth weight, asthma heredity (paternal), secondhand smoke in infancy, and season of birth had a significant impact (p-value ≤0.01). The majority of subjects stayed however within the same category of lung function between ages 8 and 16 years (in total 821/1425 = 58%). Predictors associated with having persistently low lung function were gestational age, secondhand smoke (at 2 and 8 years of age), and factors related to lower respiratory tract infections in infancy.

CONCLUSIONS

In summary, rather few exposures in childhood were identified to have a significant impact on lung function growth between childhood and adolescence. Our data support previous study findings indicating that lung function development is influenced by factors before birth and in infancy, including second hand tobacco smoke.