Physical activity, sleep and risk of respiratory infections: A Swedish cohort study

OBJECTIVES

Previous studies found higher levels of physical activity to be protective against infections and that short and long sleep negatively affects the immune response. However, these relationships remain debatable. We aimed to investigate if physical activity and sleep habits affect incidence of upper respiratory tract infections (URTI) in a prospective cohort study.

METHODS

A total of 2,038 adults aged 25-64 years served as a random sample of the gainfully employed population of an industrial town in Sweden. Physical activity and sleep habits were estimated through self-reported questionnaires. Physical activity was expressed as metabolic energy turnover hours per day. Sleep was assessed as number of hours slept per night and its perceived quality. URTI outcome was prospectively self-reported during a 9-month follow-up period. Associations of physical activity and sleep with URTI were estimated using hurdle regression models adjusted for potential confounders.

RESULTS

During 1,583 person-years 1,597 URTI occurred, resulting in an incidence of 1.01 infections/person-year (95% CI 0.96-1.06). The fitted regression models did not provide support for an association with physical activity or sleep habits. Factors positively associated with experiencing URTI were having children ≤ 6 years, female gender, higher education and treatment for allergy, asthma or lung cancer. Having children ≤ 6 years and female gender were related to a higher number of URTI among those experiencing URTI.

CONCLUSIONS

We did not find any association between physical activity, sleep duration or sleep quality and the occurrence of upper respiratory tract infections in adult Swedish population.

Cigarette- and snus-modified association between unprotected exposure to noise from hunting rifle caliber weapons and high frequency hearing loss. A cross-sectional study among swedish hunters

Aim:

To investigate in this cross-sectional study among Swedish hunters if tobacco use modifies the previously observed association, expressed as prevalence ratio (PR), between unprotected exposure to impulse noise from hunting rifle caliber (HRC) weapons and high-frequency hearing impairment (HFHI).

Settings and Design:

A nationwide cross-sectional epidemiologic study was conducted among Swedish sport hunters in 2012.

Materials and Methods:

The study was Internet-based and consisted of a questionnaire and an Internet-based audiometry test.

Results:

In all, 202 hunters completed a questionnaire regarding the hearing test. Associations were modeled using Poisson regression. Current, daily use of tobacco was reported by 61 hunters (19 used cigarettes, 47 moist snuff, and 5 both). Tobacco users tended to be younger, fire more shots with HRC weapons, and report more hunting days. Their adjusted PR (1–6 unprotected HRC shots versus 0) was 3.2 (1.4–6.7), P = 0.01. Among the nonusers of tobacco, the corresponding PR was 1.3 (0.9–1.8), P = 0.18. P value for the interaction was 0.01. The importance of ear protection could not be quantified among hunters with HRC weapons because our data suggested that the HFHI outcome had led to changes in the use of such protection. Among hunters using weapons with less sound energy, however, no or sporadic use of hearing protection was linked to a 60% higher prevalence of HFHI, relative to habitual use.

Conclusion:

Tobacco use modifies the association between exposure to unprotected impulse noise from HRC weapons and the probability of having HFHI among susceptible hunters. The mechanisms remain to be clarified, but because the effect modification was apparent also among the users of smokeless tobacco, combustion products may not be critical for this effect.

Association of Donor Age and Sex With Survival of Patients Receiving Transfusions

IMPORTANCE

Following animal model data indicating the possible rejuvenating effects of blood from young donors, there have been at least 2 observational studies conducted with humans that have investigated whether donor age affects patient outcomes. Results, however, have been conflicting.

OBJECTIVE

To study the association of donor age and sex with survival of patients receiving transfusions.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort study based on the Scandinavian Donations and Transfusions database, with nationwide data, was conducted for all patients from Sweden and Denmark who received at least 1 red blood cell transfusion of autologous blood or blood from unknown donors between January 1, 2003, and December 31, 2012. Patients were followed up from the first transfusion until death, emigration, or end of follow-up. Data analysis was performed from September 15 to November 15, 2016.

EXPOSURES

The number of transfusions from blood donors of different age and sex. Exposure was treated time dependently throughout follow-up.

MAIN OUTCOMES AND MEASURES

Hazard ratios (HRs) for death and adjusted cumulative mortality differences, both estimated using Cox proportional hazards regression.

RESULTS

Results of a crude analysis including 968 264 transfusion recipients (550 257 women and 418 007 men; median age at first transfusion, 73.0 years [interquartile range, 59.8-82.4 years]) showed a U-shaped association between age of the blood donor and recipient mortality, with a nadir in recipients for the most common donor age group (40-49 years) and significant and increasing HRs among recipients of blood from donors of successively more extreme age groups (<20 years: HR, 1.12; 95% CI, 1.10-1.14; ≥70 years: HR, 1.25; 95% CI, 1.08-1.44). Higher mortality was also noted among recipients of blood from female donors (HR, 1.07; 95% CI, 1.07-1.07). Adjustments for number of transfusions with a linear term attenuated the associations, but the increased mortality for recipients of blood from young, old, and female donors was not eliminated. Closer examination of the association between number of transfusions and mortality revealed a nonlinear pattern. After adjustments to accommodate nonlinearity, donor age and sex were no longer associated with patient mortality.

CONCLUSIONS AND RELEVANCE

Donor age and sex were not associated with patient survival and need not be considered in blood allocation. Any comparison between common and less common categories of transfusions will inevitably be confounded by the number of transfusions, which drives the probability of receiving the less common blood components. Previous positive findings regarding donor age and sex are most likely explained by residual confounding.

Snus use, smoking and survival among prostate cancer patients

Smoking is associated with prostate cancer mortality. The Scandinavian smokeless tobacco product snus is a source of nicotine but not the combustion products of smoke and has not been studied with respect to prostate cancer survival. The study is nested among 9,582 men with incident prostate cancer within a prospective cohort of 336,381 Swedish construction workers. Information on tobacco use was collected at study entry between 1971 and 1992, and categorized into (i) never users of any tobacco, (ii) exclusive snus: ever users of snus only, (iii) exclusive smokers: ever smokers (cigarette, cigar and/or pipe) only and (iv) ever users of both snus and smoking. Hazard ratios for prostate cancer-specific and total mortality for smoking and snus use based on Cox proportional hazards models adjusted for age, calendar period at diagnosis and body mass index at baseline. During 36 years of follow-up, 4,758 patients died-2,489 due to prostate cancer. Compared to never users of tobacco, exclusive smokers were at increased risk of prostate cancer mortality (HR 1.15, 95% CI: 1.05-1.27) and total mortality (HR 1.17, 95% CI: 1.09-1.26). Exclusive snus users also had increased risks for prostate cancer mortality (HR 1.24, 95% CI: 1.03-1.49) and total mortality (HR 1.19, 95% CI: 1.04-1.37). Among men diagnosed with nonmetastatic disease, the HR for prostate cancer death among exclusive snus users was 3.17 (95% CI: 1.66-6.06). The study is limited by a single assessment of tobacco use prior to diagnosis. Snus use was associated with increased risks of prostate cancer and total mortality among prostate cancer patients. This suggests that tobacco-related components such as nicotine or tobacco-specific carcinogens may promote cancer progression independent of tobacco's combustion products.

Helicobacter pylori infection, chronic corpus atrophic gastritis and pancreatic cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort: A nested case-control study

The association between H. pylori infection and pancreatic cancer risk remains controversial. We conducted a nested case-control study with 448 pancreatic cancer cases and their individually matched control subjects, based on the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort, to determine whether there was an altered pancreatic cancer risk associated with H. pylori infection and chronic corpus atrophic gastritis. Conditional logistic regression models were applied to calculate odds ratios (ORs) and corresponding 95% confidence intervals (CIs), adjusted for matching factors and other potential confounders. Our results showed that pancreatic cancer risk was neither associated with H. pylori seropositivity (OR = 0.96; 95% CI: 0.70, 1.31) nor CagA seropositivity (OR = 1.07; 95% CI: 0.77, 1.48). We also did not find any excess risk among individuals seropositive for H. pylori but seronegative for CagA, compared with the group seronegative for both antibodies (OR = 0.94; 95% CI: 0.63, 1.38). However, we found that chronic corpus atrophic gastritis was non-significantly associated with an increased pancreatic cancer risk (OR = 1.35; 95% CI: 0.77, 2.37), and although based on small numbers, the excess risk was particularly marked among individuals seronegative for both H. pylori and CagA (OR = 5.66; 95% CI: 1.59, 20.19, p value for interaction < 0.01). Our findings provided evidence supporting the null association between H. pylori infection and pancreatic cancer risk in western European populations. However, the suggested association between chronic corpus atrophic gastritis and pancreatic cancer risk warrants independent verification in future studies, and, if confirmed, further studies on the underlying mechanisms.

Transmission of Neurodegenerative Disorders Through Blood Transfusion: A Cohort Study

BACKGROUND

The aggregation of misfolded proteins in the brain occurs in several neurodegenerative disorders. Aberrant protein aggregation is inducible in rodents and primates by intracerebral inoculation. Possible transfusion transmission of neurodegenerative diseases has important public health implications.

OBJECTIVE

To investigate possible transfusion transmission of neurodegenerative disorders.

DESIGN

Retrospective cohort study.

SETTING

Nationwide registers of transfusions in Sweden and Denmark.

PARTICIPANTS

1 465 845 patients who received transfusions between 1968 and 2012.

MEASUREMENTS

Multivariable Cox regression models were used to estimate hazard ratios for dementia of any type, Alzheimer disease, and Parkinson disease in patients receiving blood transfusions from donors who were later diagnosed with any of these diseases versus patients who received blood from healthy donors. Whether excess occurrence of neurodegenerative disease occurred among recipients of blood from a subset of donors was also investigated. As a positive control, transmission of chronic hepatitis before and after implementation of hepatitis C virus screening was assessed.

RESULTS

Among included patients, 2.9% received a transfusion from a donor diagnosed with one of the studied neurodegenerative diseases. No evidence of transmission of any of these diseases was found, regardless of approach. The hazard ratio for dementia in recipients of blood from donors with dementia versus recipients of blood from healthy donors was 1.04 (95% CI, 0.99 to 1.09). Corresponding estimates for Alzheimer disease and Parkinson disease were 0.99 (CI, 0.85 to 1.15) and 0.94 (CI, 0.78 to 1.14), respectively. Hepatitis transmission was detected before but not after implementation of hepatitis C virus screening.

LIMITATION

Observational study design, underascertainment of the outcome, and possible insufficient statistical power.

CONCLUSION

The data provide no evidence for the transmission of neurodegenerative diseases and suggest that if transmission does occur, it is rare.

PRIMARY FUNDING SOURCE

Swedish Research Council, Swedish Heart-Lung Foundation, Swedish Society for Medical Research, and Danish Council for Independent Research.

ABO blood group and risk of cancer: A register-based cohort study of 1.6 million blood donors

INTRODUCTION

The associations between ABO blood group and cancer risk have been studied repeatedly, but results have been variable. Consistent associations have only been reported for pancreatic and gastric cancers.

MATERIALS AND METHODS

We estimated associations between different ABO blood groups and site-specific cancer risk in a large cohort of healthy blood donors from Sweden and Denmark.

RESULTS

A total of 1.6 million donors were followed over 27 million person-years (20 million in Sweden and 7 million in Denmark). We observed 119,584 cancer cases. Blood groups A, AB and B were associated either with increased or decreased risk of cancer at 13 anatomical sites (p≤0.05), compared to blood group O. Consistent with assessment using a false discovery rate approach, significant associations with ABO blood group were observed for cancer of the pancreas, breast, and upper gastrointestinal tract (mouth, salivary glands, pharynx, esophageal adenocarcinoma and stomach).

DISCUSSION

Our study reconfirms the association between ABO blood group and cancer risk and exact underlying mechanisms involved needs further research.

ABO Blood Group and Risk of Thromboembolic and Arterial Disease: A Study of 1.5 Million Blood Donors

BACKGROUND

ABO blood groups have been shown to be associated with increased risks of venous thromboembolic and arterial disease. However, the reported magnitude of this association is inconsistent and is based on evidence from small-scale studies.

METHODS AND RESULTS

We used the SCANDAT2 (Scandinavian Donations and Transfusions) database of blood donors linked with other nationwide health data registers to investigate the association between ABO blood groups and the incidence of first and recurrent venous thromboembolic and arterial events. Blood donors in Denmark and Sweden between 1987 and 2012 were followed up for diagnosis of thromboembolism and arterial events. Poisson regression models were used to estimate incidence rate ratios as measures of relative risk. A total of 9170 venous and 24 653 arterial events occurred in 1 112 072 individuals during 13.6 million person-years of follow-up. Compared with blood group O, non-O blood groups were associated with higher incidence of both venous and arterial thromboembolic events. The highest rate ratios were observed for pregnancy-related venous thromboembolism (incidence rate ratio, 2.22; 95% confidence interval, 1.77-2.79), deep vein thrombosis (incidence rate ratio, 1.92; 95% confidence interval, 1.80-2.05), and pulmonary embolism (incidence rate ratio, 1.80; 95% confidence interval, 1.71-1.88).

CONCLUSIONS

In this healthy population of blood donors, non-O blood groups explain >30% of venous thromboembolic events. Although ABO blood groups may potentially be used with available prediction systems for identifying at-risk individuals, its clinical utility requires further comparison with other risk markers.

Blood donation and risk of polycythemia vera

BACKGROUND

It has been suggested that blood donors could have an increased risk of polycythemia vera (PV). However, no study has assessed whether frequent donors have a higher PV risk than less frequent donors.

STUDY DESIGN AND METHODS

From the Scandinavian Donations and Transfusions (SCANDAT2) database, we established a cohort of blood donors who had donated whole blood at least once between 1980 and 2012. Within this cohort we first assessed the risk of PV, comparing the donors to the general population using standardized incidence ratios (SIRs) with corresponding 95% confidence intervals (CIs). To assess the association between frequency of blood donation and risk of PV we then conducted a case-control study nested within the cohort, where we compared prior donation activity among donors who were diagnosed with PV and matched controls. Here odds ratios (ORs) were used as measures of relative risk comparing donors with different donation frequency.

RESULTS

Among 1.4 million donors in the cohort a total of 271 donors developed PV, yielding a SIR of 1.00 (95% CI, 0.89-1.13) compared to the general population. The nested case-control study showed no association between donation frequency and risk of PV. The OR of PV comparing donors who had made at least 33 donations in the period from 3 to 22 years before diagnosis of the case, to donors with one to eight donations in the same period was 1.01 (95% CI, 0.51-1.97).

CONCLUSIONS

We find no evidence of excess risk of PV among blood donors or of an association between donation frequency and PV risk.

Shooting history and presence of high-frequency hearing impairment in swedish hunters: A cross-sectional internet-based observational study

The aim of this cross-sectional study among Swedish hunters was to examine the association between shooting history and presence of high-frequency hearing impairment (HFHI). All hunters registered with an e-mail address in the membership roster of the Swedish Hunters’ Association were invited via e-mail to a secure website with a questionnaire and an Internet-based audiometry test. Associations, expressed as prevalence ratio (PR), were multivariately modelled using Poisson regression. The questionnaire was answered by 1771 hunters (age 11-91 years), and 202 of them also completed the audiometry test. Subjective severe hearing loss was reported by 195/1771 (11%), while 23/202 (11%) exhibited HFHI upon testing with Internet-based audiometry. As many as 328/1771 (19%) had never used hearing protection during hunting. In the preceding 5 years, 785/1771 (45%), had fired >6 unprotected gunshots with hunting rifle calibers. The adjusted PR of HFHI when reporting 1-6 such shots, relative to 0, was 1.5 [95% confidence interval (CI) 1.1-2.1; P = 0.02]. We could not verify any excessive HFHI prevalence among 89 hunters reporting unprotected exposure to such gunshot noise >6 times. Nor did the total number of reported rifle shots seem to matter. These findings support the notion of a wide variation in individual susceptibility to impulse noise; that significant sound energy, corresponding to unprotected noise from hunting rifle calibers, seems to be required; that susceptible individuals may sustain irreversible damage to the inner ear from just one or a few shots; and that use of hearing protection should be encouraged from the first shot with such weapons.

Increase in the Prevalence of Atrophic Gastritis Among Adults Age 35 to 44 Years Old in Northern Sweden Between 1990 and 2009

BACKGROUND & AIMS

Atrophic corpus gastritis (ACG) is believed to be an early precursor of gastric adenocarcinoma. We aimed to investigate trends of ACG in Northern Sweden, from 1990 through 2009, and to identify possible risk factors.

METHODS

We randomly selected serum samples collected from 5284 participants in 1990, 1994, 1999, 2004, and 2009, as part of the population-based, cross-sectional Northern Sweden Multinational Monitoring of Trends and Determinants in Cardiovascular Disease study (ages, 35-64 y). Information was collected on sociodemographic, anthropometric, lifestyle, and medical factors using questionnaires. Serum samples were analyzed for levels of pepsinogen I to identify participants with functional ACG; data from participants with ACG were compared with those from frequency-matched individuals without ACG (controls). Blood samples were analyzed for antibodies against Helicobacter pylori and Cag pathogenicity island protein A. Associations were estimated with unconditional logistic regression models.

RESULTS

Overall, 305 subjects tested positive for functional ACG, based on their level of pepsinogen I. The prevalence of ACG in participants age 55 to 64 years old decreased from 124 per 1000 to 49 per 1000 individuals between 1990 and 2009. However, the prevalence of ACG increased from 22 per 1000 to 64 per 1000 individuals among participants age 35 to 44 years old during this time period. Cag pathogenicity island protein A seropositivity was associated with risk for ACG (odds ratio, 2.29; 95% confidence interval, 1.69-3.12). Other risk factors included diabetes, low level of education, and high body mass index. The association between body mass index and ACG was confined to individuals age 35 to 44 years old; in this group, overweight and obesity were associated with a 2.8-fold and a 4.7-fold increased risk of ACG, respectively.

CONCLUSIONS

Among residents of Northern Sweden, the prevalence of ACG increased from 1990 through 2009, specifically among adults age 35 to 44 years old. The stabilizing seroprevalence of H pylori and the increasing prevalence of overweight and obesity might contribute to this unexpected trend. Studies are needed to determine whether these changes have affected the incidence of gastric cancer.

Incidence of gastric cancer among patients with gastric precancerous lesions: observational cohort study in a low risk Western population

OBJECTIVE

To accurately measure the incidence of gastric cancer among patients with gastric precancerous lesions, and to quantify the excess incidence in comparison with people with normal mucosa on endoscopy and a general population.

DESIGN

Population based cohort study.

SETTING

Population of Sweden using data from its national disease registers.

PARTICIPANTS

405,172 patients who had gastric biopsy samples taken for non-malignant indications between 1979 and 2011.

MAIN OUTCOME MEASURES

Incidence of gastric cancer, reported separately for patients with different mucosal changes in biopsy samples. Standardised incidence ratios provided estimation of the relative risk, using the general Swedish population as reference; and hazard ratios were derived from Cox regression modelling for internal comparisons with patients with normal gastric mucosa.

RESULTS

After excluding the first two years of follow-up, 1599 cases of gastric cancer were identified. The annual crude incidence of gastric cancer was 20 × 10(-5) for those in the normal mucosa group (standardised incidence ratio 1.0), 42 × 10(-5) for those with minor changes (1.5), 59 × 10(-5) for the gastritis group (1.8), 100 × 10(-5) for the atrophic gastritis group (2.8), 129 × 10(-5) for the intestinal metaplasia group (3.4), and 263 × 10(-5) for the dysplasia group (6.5). Cox regression modelling confirmed that excess risks increased monotonically with progressive severity of gastric lesions, with the highest hazard ratio of 10.9 (dysplasia versus normal mucosa, 95% confidence interval 7.7 to 15.4). The increased incidence was stable throughout the follow-up period, and the gaps between cumulative incidence curves grew continuously.

CONCLUSIONS

Among patients who undergo gastroscopy with biopsy for clinical indications, approximately 1 in 256 with normal mucosa, 1 in 85 with gastritis, 1 in 50 with atrophic gastritis, 1 in 39 with intestinal metaplasia, and 1 in 19 with dysplasia will develop gastric cancer within 20 years. These numbers, along with cost-benefit analyses, should guide future surveillance policies for these particular patient groups.

Blood donation and blood donor mortality after adjustment for a healthy donor effect

BACKGROUND

Studies have repeatedly demonstrated that blood donors experience lower mortality than the general population. While this may suggest a beneficial effect of blood donation, it may also reflect the selection of healthy persons into the donor population. To overcome this bias, we investigated the relation between blood donation frequency and mortality within a large cohort of blood donors. In addition, our analyses also took into consideration the effects of presumed health differences linked to donation behavior.

STUDY DESIGN AND METHODS

Using the Scandinavian Donation and Transfusion database (SCANDAT), we assessed the association between annual number of donations in 5-year windows and donor mortality by means of Poisson regression analysis. The analyses included adjustment for demographic characteristics and for an internal healthy donor effect, estimated among elderly donors exempted from continued donation because of age criteria.

RESULTS

Statistical analyses included 1,182,495 donors of whom 15,401 died during 9,526,627 person-years of follow-up. Analyses adjusted only for demographic characteristics showed a 18.6% reduction in mortality per additional annual donation (95% confidence interval [CI], 16.8%-20.4%). After additional adjustment for the internal healthy donor effect, each additional annual donation was associated with a 7.5% decreased mortality risk 7.5% (95% CI, 5.7%-9.4%).

CONCLUSION

We observed an inverse relationship between donation frequency and mortality. The magnitude of the association was reduced after adjustment for an estimate of self-selection in the donor population. Our observations indicate that repeated blood donation is not associated with premature death, but cannot be interpreted as conclusive evidence of a beneficial health effect.

Associations of hand-washing frequency with incidence of acute respiratory tract infection and influenza-like illness in adults: a population-based study in Sweden

BACKGROUND

Frequent hand-washing is standard advice for avoidance of respiratory tract infections, but the evidence for a preventive effect in a general community setting is sparse. We therefore set out to quantify, in a population-based adult general population cohort, the possible protection against acute respiratory tract infections (ARIs) conferred by a person's self-perceived hand-washing frequency.

METHODS

During the pandemic influenza season from September 2009 through May 2010, a cohort of 4365 adult residents of Stockholm County, Sweden, reported respiratory illnesses in real-time. A questionnaire about typical contact and hand-washing behaviour was administered at the end of the period (response rate 70%).

RESULTS

There was no significant decrease in ARI rates among adults with increased daily hand-washing frequency: Compared to 2-4 times/day, 5-9 times was associated with an adjusted ARI rate ratio (RR) of 1.08 (95% confidence interval [CI] 0.87-1.33), 10-19 times with RR = 1.22 (CI 0.97-1.53), and ≥20 times with RR = 1.03 (CI 0.81-1.32). A similar lack of effect was seen for influenza-like illness, and in all investigated subgroups. We found no clear effect modification by contact behaviour. Health care workers exhibited rate ratio point estimates below unity, but no dose-risk trend.

CONCLUSIONS

Our results suggest that increases in what adult laymen perceive as being adequate hand-washing may not significantly reduce the risk of ARIs. This might have implications for the design of public health campaigns in the face of threatening outbreaks of respiratory infections. However, the generalizability of our results to non-pandemic circumstances should be further explored.

Dose-response relationship of total and leisure time physical activity to risk of heart failure: a prospective cohort study

BACKGROUND

The nature of the association between levels of physical activity and risk of heart failure is little known. We investigated nonlinear associations of total and leisure time physical activity with risk of heart failure.

METHODS AND RESULTS

In 1997, 39 805 persons without heart failure completed a questionnaire of lifestyle factors and medical history. We used Cox regression models to investigate total (adjusting for education and previous myocardial infarction) and direct (multivariable-adjusted) effects of self-reported total and leisure time physical activity on risk of heart failure of any cause and heart failure of nonischemic origin. Heart failure diagnoses were obtained until December 31, 2010. Higher leisure time physical activity was associated with lower risk of heart failure of any cause; hazard ratio of the total effect of leisure time physical activity was for fifth versus first quintile 0.54; 95% confidence interval was 0.44 to 0.66. The direct effect was similar. High total daily physical activity level was associated with lower risk of heart failure, although the effect was less pronounced than for leisure time physical activity (total effect hazard ratio, 0.81; 95% confidence interval, 0.69-0.95; fifth versus first quintile). A similar direct effect observed.

CONCLUSIONS

Leisure time physical activity was inversely related to risk of developing heart failure in a dose-response fashion. This was reflected in a similar but less pronounced association of total physical activity with risk of heart failure. Only part of the effects appeared to be mediated by traditional risk factors.

Gastroesophageal reflux in relation to adenocarcinomas of the esophagus: a pooled analysis from the Barrett's and Esophageal Adenocarcinoma Consortium (BEACON)

BACKGROUND

Previous studies have evidenced an association between gastroesophageal reflux and esophageal adenocarcinoma (EA). It is unknown to what extent these associations vary by population, age, sex, body mass index, and cigarette smoking, or whether duration and frequency of symptoms interact in predicting risk. The Barrett's and Esophageal Adenocarcinoma Consortium (BEACON) allowed an in-depth assessment of these issues.

METHODS

Detailed information on heartburn and regurgitation symptoms and covariates were available from five BEACON case-control studies of EA and esophagogastric junction adenocarcinoma (EGJA). We conducted single-study multivariable logistic regressions followed by random-effects meta-analysis. Stratified analyses, meta-regressions, and sensitivity analyses were also conducted.

RESULTS

Five studies provided 1,128 EA cases, 1,229 EGJA cases, and 4,057 controls for analysis. All summary estimates indicated positive, significant associations between heartburn/regurgitation symptoms and EA. Increasing heartburn duration was associated with increasing EA risk; odds ratios were 2.80, 3.85, and 6.24 for symptom durations of <10 years, 10 to <20 years, and ≥20 years. Associations with EGJA were slighter weaker, but still statistically significant for those with the highest exposure. Both frequency and duration of heartburn/regurgitation symptoms were independently associated with higher risk. We observed similar strengths of associations when stratified by age, sex, cigarette smoking, and body mass index.

CONCLUSIONS

This analysis indicates that the association between heartburn/regurgitation symptoms and EA is strong, increases with increased duration and/or frequency, and is consistent across major risk factors. Weaker associations for EGJA suggest that this cancer site has a dissimilar pathogenesis or represents a mixed population of patients.

Evaluation of an Internet-based monitoring system for influenza-like illness in Sweden

To complement traditional influenza surveillance with data on disease occurrence not only among care-seeking individuals, the Swedish Institute for Communicable Disease Control (SMI) has tested an Internet-based monitoring system (IMS) with self-recruited volunteers submitting weekly on-line reports about their health in the preceding week, upon weekly reminders. We evaluated IMS acceptability and to which extent participants represented the Swedish population. We also studied the agreement of data on influenza-like illness (ILI) occurrence from IMS with data from a previously evaluated population-based system (PBS) with an actively recruited random sample of the population who spontaneously report disease onsets in real-time via telephone/Internet, and with traditional general practitioner based sentinel and virological influenza surveillance, in the 2011-2012 and 2012-2013 influenza seasons. We assessed acceptability by calculating the participation proportion in an invited IMS-sample and the weekly reporting proportion of enrolled self-recruited IMS participants. We compared distributions of socio-demographic indicators of self-recruited IMS participants to the general Swedish population using chi-square tests. Finally, we assessed the agreement of weekly incidence proportions (%) of ILI in IMS and PBS with cross-correlation analyses. Among 2,511 invited persons, 166 (6.6%) agreed to participate in the IMS. In each season, 2,552 and 2,486 self-recruited persons participated in the IMS respectively. The weekly reporting proportion among self-recruited participants decreased from 87% to 23% (2011-2012) and 82% to 45% (2012-2013). Women, highly educated, and middle-aged persons were overrepresented among self-recruited IMS participants (p<0.01). IMS (invited and self-recruited) and PBS weekly incidence proportions correlated strongest when no lags were applied (r = 0.71 and r = 0.69, p<0.05). This evaluation revealed socio-demographic misrepresentation and limited compliance among the self-recruited IMS participants. Yet, IMS offered a reasonable representation of the temporal ILI pattern in the community overall during the 2011-2012 and 2012-2013 influenza seasons and could be a simple tool for collecting community-based ILI data.

Gastroesophageal reflux does not alter effects of body mass index on risk of esophageal adenocarcinoma

BACKGROUND & AIMS

A history of high body mass index (BMI) is associated strongly with a risk of esophageal adenocarcinoma (EAC). We investigated whether gastroesophageal reflux is involved in this association.

METHODS

We analyzed data from a population-based Swedish nationwide study of patients with a new diagnosis of EAC (n = 189) or gastroesophageal junction adenocarcinoma (n = 262), and matched controls (n = 816), from 1995 through 1997. Our analysis included data on BMI 20 years before study inclusion; maximum adult BMI; frequency, severity, and duration of gastroesophageal reflux symptoms; tumor features; and covariates (sex, age, smoking, alcohol, fruit and vegetable intake, and socioeconomic status). We conducted stratified analyses and synergy tests, adjusting for covariates.

RESULTS

Odds ratios (ORs) for EAC among subjects with a BMI of 25 or higher 20 years before inclusion, compared with those with a BMI less than 25, did not differ significantly, without or with adjustment for gastroesophageal reflux frequency (OR, 3.1; 95% confidence interval [CI], 2.2-4.4; and OR, 3.3; 95% CI, 2.2-4.8, respectively), severity (OR, 3.3; 95% CI, 2.2-4.8), or duration (OR, 3.2; 95% CI, 2.2-4.7). However, there were interactions between BMI and categories of gastroesophageal reflux. BMI appeared to have the largest effect on gastroesophageal reflux frequency (synergy index, 8.9; 95% CI, 2.3-34.1 for maximum BMI; and gastroesophageal reflux >3 times/wk).

CONCLUSIONS

Based on a population-based study, the association between BMI and EAC does not appear to be affected by symptomatic gastroesophageal reflux, although there appears to be synergy between BMI and reflux.

A CagA-independent cluster of antigens related to the risk of noncardia gastric cancer: associations between Helicobacter pylori antibodies and gastric adenocarcinoma explored by multiplex serology

Because of the differences in bacterial epitopes and host characteristics, infections with Helicobacter pylori (H. pylori) induce different immune responses. We explored the possibility that certain antibody response patterns are more closely linked to gastric adenocarcinoma (GAC) than others. In a Swedish population-based case-control study, serum samples were obtained from 268 cases and 222 controls, aged 40-79 years and frequency-matched according to age and sex. We measured antibodies against 17 H. pylori proteins using multiplex serology. Associations were estimated with multivariably adjusted logistic regression models, using odds ratio (OR) with 95% confidence interval (CI) as measures of relative risk. Associations were essentially confined to non-cardia GAC but did not differ significantly between intestinal and diffuse subtypes. Point estimates for all antibodies were above unity, 15 significant with top three being CagA (OR = 9.2), GroEL (6.6), HyuA (3.6). ORs were substantially attenuated in individuals with chronic atrophic gastritis. Principal component analysis identified two significant factors: a CagA-dominant factor (antibodies against CagA, VacA and Omp as prominent markers), and a non-CagA factor (antibodies against NapA and Catalase as prominent markers). Both factors showed dose-dependent associations with non-cardia GAC risk (CagA-dominant factor, highest vs. lowest quartiles, OR = 16.2 [95% CI 4.8-54.9]; non-CagA factor OR = 5.3 [95% CI 2.1-13.3]). Overall, our results confirm that serum antibodies against different H. pylori proteins are associated with the presence of non-cardia GAC. Although strongest association is detected by antibodies against CagA and covarying proteins, a pattern of antibodies unrelated to CagA is also significantly linked to the risk of non-cardia GAC.

A genome-wide association study identifies new susceptibility loci for esophageal adenocarcinoma and Barrett's esophagus

Esophageal adenocarcinoma is a cancer with rising incidence and poor survival. Most such cancers arise in a specialized intestinal metaplastic epithelium, which is diagnostic of Barrett's esophagus. In a genome-wide association study, we compared esophageal adenocarcinoma cases (n = 2,390) and individuals with precancerous Barrett's esophagus (n = 3,175) with 10,120 controls in 2 phases. For the combined case group, we identified three new associations. The first is at 19p13 (rs10419226: P = 3.6 × 10(-10)) in CRTC1 (encoding CREB-regulated transcription coactivator), whose aberrant activation has been associated with oncogenic activity. A second is at 9q22 (rs11789015: P = 1.0 × 10(-9)) in BARX1, which encodes a transcription factor important in esophageal specification. A third is at 3p14 (rs2687201: P = 5.5 × 10(-9)) near the transcription factor FOXP1, which regulates esophageal development. We also refine a previously reported association with Barrett's esophagus near the putative tumor suppressor gene FOXF1 at 16q24 and extend our findings to now include esophageal adenocarcinoma.

A global assessment of the oesophageal adenocarcinoma epidemic

OBJECTIVE

About 20 years ago, the scientific community was first alerted to an enigmatic increase of oesophageal adenocarcinomas in the UK and USA. Subsequently, a virtual epidemic-still unexplained-was confirmed in several western countries. Detailed descriptive data might provide clues to its causes.

DESIGN

We collected data on incident cases of oesophageal adenocarcinoma from population-based cancer registries in Australia, Europe, North America and Asia. We calculated age-standardised incidence rates and fitted log-linear Poisson models to assess annual rate of increase and to disentangle age-period-cohort effects, linear spine models to estimate rate of increase since 1985, and Joinpoint models to identify possible inflection points.

RESULTS

With considerable between-registry variation in magnitude and timing, we found a consistent dramatic increase in incidence with an observed or estimated start between 1960 and 1990. The average annual increase ranged from 3.5% in Scotland to 8.1% in Hawaii with similar proportional increase among men and women in most registries and a maintained three to sixfold higher incidence among men. Generally, calendar period was a more important determinant of incidence trends than birth cohort. Where possible to conduct, Joinpoint analyses indicated that the onset of the epidemic varied considerably even between neighbouring countries.

CONCLUSIONS

Given the preponderant period effect and the abrupt onset observed or inferred in most populations, the epidemic appears to be caused by some exposure that was first introduced around 1950. At least 30 years' variation in estimated time of onset opens prospects for hypothesis-generating ecological analyses.

The validity of self-initiated, event-driven infectious disease reporting in general population cohorts

Background

The 2009/2010 pandemic influenza highlighted the need for valid and timely incidence data. In 2007 we started the development of a passive surveillance scheme based on passive follow-up of representative general population cohorts. Cohort members are asked to spontaneously report all instances of colds and fevers as soon as they occur for up to 9 months. Suspecting that compliance might be poor, we aimed to assess the validity of self-initiated, event-driven outcome reporting over long periods.

Methods

During two 8 week periods in 2008 and 2009, 2376 and 2514 cohort members in Stockholm County were sent one-week recall questionnaires, which served as reference method.

Results

The questionnaires were completed by 88% and 86% of the cohort members. Whilst the false positive proportion (1–specificity) in the reporting was low (upper bound of the 95% confidence interval [CI] ≤2% in each season), the false negative proportion (failure to report, 1–sensitivity) was considerable (60% [95% CI 52%–67%] in each season). Still, the resulting epidemic curves for influenza-like illness compared well with those from existing General Practitioner-based sentinel surveillance in terms of shape, timing of peak, and year-to-year variation. This suggested that the error was fairly constant.

Conclusions

Passive long-term surveillance through self-initiated, event-driven outcome reporting underestimates incidence rates of common upper respiratory tract infections. However, because underreporting appears predictable, simple corrections could potentially restore validity.

Body mass index in relation to oesophageal and oesophagogastric junction adenocarcinomas: a pooled analysis from the International BEACON Consortium

BACKGROUND

Previous studies suggest an association between obesity and oesophageal (OA) and oesophagogastric junction adenocarcinomas (OGJA). However, these studies have been limited in their ability to assess whether the effects of obesity vary by gender or by the presence of gastro-oesophageal reflux (GERD) symptoms.

METHODS

Individual participant data from 12 epidemiological studies (8 North American, 3 European and 1 Australian) comprising 1997 OA cases, 1900 OGJA cases and 11 159 control subjects were pooled. Logistic regression was used to estimate study-specific odds ratios (ORs) and 95% confidence intervals (CIs) for the association between body mass index (BMI, kg/m(2)) and the risk of OA and OGJA. Random-effects meta-analysis was used to combine these ORs. We also investigated effect modification and synergistic interaction of BMI with GERD symptoms and gender.

RESULTS

The association of OA and OGJA increased directly with increasing BMI (P for trend <0.001). Compared with individuals with a BMI <25, BMI ≥40 was associated with both OA (OR 4.76, 95% CI 2.96-7.66) and OGJA (OR 3.07, 95% CI 1.89-4.99). These associations were similar when stratified by gender and GERD symptoms. There was evidence for synergistic interaction between BMI and GERD symptoms in relation to OA/OGJA risk.

CONCLUSIONS

These data indicate that BMI is directly associated with OA and OGJA risk in both men and women and in those with and without GERD symptoms. Disentangling the relationship between BMI and GERD will be important for understanding preventive efforts for OA and OGJA.

The importance of exposure rate on odds ratios by cigarette smoking and alcohol consumption for esophageal adenocarcinoma and squamous cell carcinoma in the Barrett's Esophagus and Esophageal Adenocarcinoma Consortium

BACKGROUND

Cigarette smoking is associated with esophageal adenocarcinoma (EAC), esophagogastric junctional adenocarcinoma (EGJA) and esophageal squamous cell carcinoma (ESCC), and alcohol consumption with ESCC. However, no analyses have examined how delivery rate modifies the strength of odds ratio (OR) trends with total exposure, i.e., the impact on the OR for a fixed total exposure of high exposure rate for short duration compared with low exposure rate for long duration.

METHODS

The authors pooled data from 12 case-control studies from the Barrett's Esophagus and Esophageal Adenocarcinoma Consortium (BEACON), including 1242 (EAC), 1263 (EGJA) and 954 (ESCC) cases and 7053 controls, modeled joint ORs for cumulative exposure and exposure rate for cigarette smoking and alcohol consumption, and evaluated effect modification by sex, body mass index (BMI), age and self-reported acid reflux.

RESULTS

For smoking, all sites exhibited inverse delivery rate effects, whereby ORs with pack-years increased, but trends weakened with increasing cigarettes/day. None of the examined factors modified associations, except for ESCC where younger ages at diagnosis enhanced smoking effects (P<0.01). For EAC and EGJA, ORs with drink-years exhibited inverse associations in <5 drinks/day consumers and no association in heavier consumers. For ESCC, ORs with drink-years increased, with trends strengthening with greater drinks/day. There was no significant effect modification, except for EAC and EGJA where acid reflux mitigated the inverse associations (P=0.02). For ESCC, younger ages at diagnosis enhanced drinking-related ORs (P<0.01).

CONCLUSIONS

Patterns of ORs by pack-years and drink-years, delivery rate effects and effect modifiers revealed common as well as distinct etiologic elements for these diseases.

Comparing different strategies for timing of dialysis initiation through inverse probability weighting

Dialysis has been used in the treatment of patients with end-stage renal disease since the 1960s. Recently, several large observational studies have been conducted to assess whether early initiation of dialysis prolongs survival, as compared with late initiation. However, these studies have used analytic approaches which are likely to suffer from either lead-time bias or immortal-time bias. In this paper, the authors demonstrate that recently developed methods in the causal inference literature can be used to avoid both types of bias and accurately estimate the ideal time for dialysis initiation from observational data. This is illustrated using data from a nationwide population-based cohort of patients with chronic kidney disease in Sweden (1996-2003).

A method for metagenomics of Helicobacter pylori from archived formalin-fixed gastric biopsies permitting longitudinal studies of carcinogenic risk

The human microbiota has come into focus in the search for component causes of chronic diseases, such as gastrointestinal cancers. Presumably long induction periods and altered local environments after disease onset call for the development of methods for characterization of microorganisms colonizing the host decades before disease onset. Sequencing of microbial genomes in old formalin-fixed and paraffin-embedded (FFPE) gastrointestinal biopsies provides a means for such studies but is still challenging. Here we report a method based on laser capture micro-dissection and modified Roche 454 high-throughput pyrosequencing to obtain metagenomic profiles of Helicobacter pylori. We applied this method to two 15 year old FFPE biopsies from two patients. Frozen homogenized biopsies from the same gastroscopy sessions were also available for comparison after re-culture of H. pylori. For both patients, H. pylori DNA dissected from FFPE sections had ∼96.4% identity with culture DNA from the same patients, while only ∼92.5% identity with GenBank reference genomes, and with culture DNA from the other patient. About 82% and 60% of the predicted genes in the two genomes were captured by at least a single sequencing read. Along with sequences displaying high similarity to known H. pylori genes, novel and highly variant H. pylori sequences were identified in the FFPE sections by our physical enrichment approach, which would likely not have been detected by a sequence capture approach. The study demonstrates the feasibility of longitudinal metagenomic studies of H. pylori using decade-preserved FFPE biopsies.

Smokeless tobacco (snus) and risk of heart failure: results from two Swedish cohorts

BACKGROUND

Oral moist snuff (snus) is discussed as a safer alternative to smoking, and its use is increasing. Based on its documented effect on blood pressure, we hypothesized that use of snus increases the risk of heart failure.

DESIGN

Two independent Swedish prospective cohorts; the Uppsala Longitudinal Study of Adult Men (ULSAM), a community-based sample of 1076 elderly men, and the Construction Workers Cohort (CWC), a sample of 118,425 never-smoking male construction workers.

METHODS

Cox proportional hazards models were used to investigate possible associations of snus use with risk of a first hospitalization for heart failure.

RESULTS

In ULSAM, 95 men were hospitalized for heart failure, during a median follow up of 8.9 years. In a model adjusted for established risk factors including past and present smoking exposure, current snus use was associated with a higher risk of heart failure [hazard ratio (HR) 2.08, 95% confidence interval (CI) 1.03-4.22] relative to non-use. Snus use was particularly associated with risk of non-ischaemic heart failure (HR 2.55, 95% CI 1.12-5.82). In CWC, 545 men were hospitalized for heart failure, during a median follow up of 18 years. In multivariable-adjusted models, current snus use was moderately associated with a higher risk of heart failure (HR 1.28, 95% CI 1.00-1.64) and non-ischaemic heart failure (HR 1.28, 95% CI 0.97-1.68) relative to never tobacco use.

CONCLUSION

Data from two independent cohorts suggest that use of snus may be associated with a higher risk of heart failure.

Alcohol intake and risk of oesophageal adenocarcinoma: a pooled analysis from the BEACON Consortium

BACKGROUND AND AIMS

Alcohol intake is a strong and well established risk factor for oesophageal squamous cell carcinoma (OSCC), but the association with oesophageal adenocarcinoma (OA) or adjacent tumours of the oesophagogastric junction (OGJA), remains unclear. Therefore, the association of alcohol intake with OSCC, OA, and OGJA was determined in nine case-control studies and two cohort studies of the Barrett's Esophagus and Esophageal Adenocarcinoma Consortium (BEACON).

MATERIALS AND METHODS

Information was collected on alcohol intake, age, sex, education, body mass index, gastro-oesophageal reflux, and tobacco smoking from each study. Along with 10,854 controls, 1821 OA, and 1837 OGJA, seven studies also collected OSCC cases (n=1016). Study specific ORs and 95% CIs were calculated from multivariate adjusted logistic regression models for alcohol intake in categories compared to non-drinkers. Summary risk estimates were obtained by random effects models. Results No increase was observed in the risk of OA or OGJA for increasing levels of any of the alcohol intake measures examined. ORs for the highest frequency category (≥ 7 drinks per day) were 0.97 (95% CI 0.68 to 1.36) for OA and 0.77 (95% CI = 0.54 to 1.10) for OGJA. Suggestive findings linked moderate intake (eg, 0.5 to <1 drink per day) to decreased risk of OA (OR 0.63, 95% CI 0.41 to 0.99) and OGJA (OR 0.78, 95% CI 0.62 to 0.99). In contrast, alcohol intake was strongly associated with increased risk of OSCC (OR for ≥ 7 drinks per day 9.62, 95% CI 4.26 to 21.71).

CONCLUSIONS

In contrast to OSCC, higher alcohol consumption was not associated with increased risk of either OA or OGJA. The apparent inverse association observed with moderate alcohol intake should be evaluated in future prospective studies.

H. pylori seropositivity before age 40 and subsequent risk of stomach cancer: a glimpse of the true relationship?

Stomach carcinogenesis involves mucosal and luminal changes that favor spontaneous disappearance of Helicobacter pylori. Therefore, the association between the infection and cancer risk might typically be underestimated. As acquisition of the infection almost invariably occurs before adulthood, the serostatus at age 16–40 should best reflect the lifetime occurrence of the infection. We therefore conducted a case-control study nested within a historic cohort of about 400,000 individuals who donated sera before age 40 to either of two large Swedish Biobanks between 1968 and 2006, and whose records were linked to complete nationwide registers. For each stomach adenocarcinoma case occurring at least 5 years after serum donation 2 controls were selected matched on age, sex and year of donation and biobank. Serum immunoglobulin G antibodies against H. pylori cell-surface antigens (Hp-CSAs) were measured with an enzyme–linked immunosorbent assay and antibodies against CagA with an immunoblot assay. Conditional logistic regression models were used to estimate odds ratios (ORs) for stomach adenocarcinoma among H. pylori infected relative to uninfected. We confirmed 59 incident cases of stomach adenocarcinoma (41 non-cardia tumors) during follow-up. ORs for non-cardia stomach adenocarcinoma among subjects with Hp-CSA antibodies (regardless of CagA serostatus), antibodies against CagA (regardless of Hp-CSA serostatus), and antibodies to both, relative to those who were seronegative to both, were 17.1 (95% confidence interval [CI] 4.0–72.9), 10.9 (95% CI 3.2–36.9), and 48.5 (95% CI 5.8–407.4), respectively. H. pylori infection is a much stronger risk factor for non-cardia stomach adenocarcinoma than initially realized. However, further studies are needed to answer whether it is a necessary cause, as the possibility of misclassification of H. pylori status could not be ruled out in our study.

No survival benefit from early-start dialysis in a population-based, inception cohort study of Swedish patients with chronic kidney disease

OBJECTIVE

To investigate how the timing of dialysis initiation is associated with mortality.

DESIGN

Population-based, prospective, observational cohort study.

SETTING

Clinical laboratories (n = 69) provided information on all patients in Sweden whose serum creatinine level for the first time and exceeded 3.4 mg dL(-1) (men) or 2.8 mg dL(-1) (women) between 20 May 1996 and 31 May 1998.

SUBJECTS

All patients (n = 901), aged 18-74 years, in whom the cause of serum creatinine elevation was chronic kidney disease, were included in the study; participants were interviewed and followed for 5-7 years.

MAIN OUTCOME MEASURES

Information on date of death was obtained from a national Swedish population register. Early-start dialysis [estimated glomerular filtration rate from serum creatinine (eGFR) ≥7.5 mL min(-1) per 1.73 m(2)] was compared to late start of dialysis (eGFR <7.5 mL min(-1) per 1.73 m(2)), and no dialysis. Relative risk [hazard ratio (HR)] of death was modelled with time-dependent multivariate Cox proportional hazards regression.

RESULTS

Mean eGFR was 16.1 mL min(-1) per 1.73 m(2) at inclusion and 7.6 mL min(-1) per 1.73 m(2) at the start of dialysis. Among the 385 patients who started dialysis late, 36% died during follow-up compared to 52% of 323 who started early. The adjusted HR for death was 0.84 [95% confidence interval (CI) 0.64, 1.10] among late versus early starters. The mortality among nondialysed patients increased significantly at eGFR below 7.5 mL min(-1) per 1.73 m(2) (HR 4.65; 95% CI 2.28, 9.49; compared to eGFR 7.5-10 mL min(-1) per 1.73 m(2)). After the start of dialysis, the mortality rate further increased. Compared to nondialysed patients with eGFR ≤15 mL min(-1) per 1.73 m(2), adjusted HR was 2.65 (95% CI 1.80, 3.89) for patients receiving dialysis.

CONCLUSION

We found no survival benefit from early initiation of dialysis.

Smoking, snus use and risk of right- and left-sided colon, rectal and anal cancer: a 37-year follow-up study

Although some authorities consider smoking to be an established risk factor for colorectal cancer, the international literature is not entirely consistent. Further, only 1 study has addressed the association with smokeless tobacco and none with Scandinavian moist snuff (snus). This retrospective cohort study included 336,381 male Swedish construction workers with detailed information on tobacco use at cohort entry in 1971-1992. Complete follow-up through 2007 was accomplished by means of linkage to population and health registers. Hazard ratios (HRs) and 95% confidence intervals (CIs) derived from Cox proportional hazards regression models estimated relative risks, adjusted for age and body mass index. Subjects who were never-users of any tobacco served as reference. After up to 37 years of follow-up, pure smoking was associated with a marginally increased risk of colon cancer (HR 1.08, 95% CI 0.99-1.19), a modestly elevated risk of rectal cancer (HR 1.16, 95% CI 1.04-1.30) and a substantial excess risk of anal cancer (HR 2.41, 95% CI 1.06-5.48). Snus use was not significantly associated with an increased risk of colorectal or anal cancer, although the point estimate for colon cancer was similar to that observed among smokers. Swedish data provide meager support for the association between tobacco use and colorectal cancer. A general tendency among Swedish men to quit smoking in recent decades might have attenuated true associations. A link between smoking and anal cancer was confirmed.

Risk of gastric cancer and peptic ulcers in relation to ABO blood type: a cohort study

Blood group A was found to be associated with gastric cancer in the 1950s. Strikingly, for peptic ulcers an increased risk has been shown for blood group O. However, previous investigations have generally been poorly conducted and have failed to take a unifying approach to these observations. Using the Scandinavian Donations and Transfusions (referred to as "SCANDAT") database, the authors established a cohort of Swedish and Danish blood donors with known blood type and followed these for the occurrence of gastric cancer and peptic ulcers through December 31, 2002. Cases were ascertained by using nationwide cancer and hospital registers. Altogether, 1,089,022 donors were followed for up to 35 years, during which 688 gastric cancer cases and 5,667 peptic ulcer cases accrued. Poisson regression analyses confirmed an increased risk of gastric cancer among individuals with blood group A (incidence rate ratio = 1.20, 95% confidence interval: 1.02, 1.42) and conversely that peptic ulcer risk was instead highest among those with blood group O. In this large, population-based cohort study, the authors have confirmed the association between blood group A and gastric cancer. In addition, they give further support to the notion that individuals with blood group O have a higher risk of peptic ulcers than those with other blood groups.

National surveillance of surgical-site infection through register-based analysis of antibiotic use after inguinal hernia repair

BACKGROUND

Systematic surveillance of surgical-site infections is not standard. The aim of this retrospective cohort study was to evaluate the feasibility of using existing national health registers for surveillance of postoperative antibiotic treatment suggestive of surgical-site infection.

METHODS

Data from national registers on hospital admissions and drug use were combined. Antibiotic purchases by 8856 patients subject to ambulatory care for inguinal hernia repair in Sweden during 2006 were ascertained during a 30-day interval immediately after surgery (postsurgical period) and in an 11-month control period (6 months before and 5 months after the postsurgical period).

RESULTS

The incidence of first purchases of skin and soft tissue antibiotics was 245 per 8697 person-months in the first postoperative month and 180 per 52 612 person-months in the preoperative control period, representing a 1-month risk difference of 2.4 (95 per cent confidence interval (c.i.) 2.0 to 2.7) per cent. Hence, a 1-month risk of 2.4 per cent could be attributed tentatively to the surgery. The rate of episodes with antibiotics used mainly for skin and soft tissue infection was sevenfold higher in the first postoperative month than in the control period (rate ratio 7.01, 95 per cent c.i. 5.94 to 8.27).

CONCLUSION

The risk of antibiotic treatment during the postsurgical period was of the same order of magnitude as infection rates reported in the Swedish Hernia Register and review studies. Surveillance of postoperative antibiotic use may be considered as a resource-saving surrogate marker for surgical-site infections or an indicator of inappropriate use.

Short-term natural history in women with symptoms indicative of pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

Information about the natural history of pelvic organ prolapse (POP) is scarce.

METHODS

This was a prospective cohort study of 160 women (mean age 56 years), whose answers in a population-based survey investigation indicated presence of symptomatic prolapse (siPOP), and 120 women without siPOP (mean age 51 years).

RESULTS

Follow-up questionnaire was completed by 87%, and 67% underwent re-examination according to pelvic organ prolapse quantification (POP-Q) system after 5 years. Among re-examining siPOP women, 47% had an unchanged POP-Q stage, 40% showed regression, and 13% showed progression. The key symptom "feeling of a vaginal bulge" remained unchanged in 30% of women with siPOP, 64% improved by at least one step on our four-step rating scale, and 6% deteriorated. Among control women, siPOP developed in 2%. No statistically significant relationship emerged between changes in anatomic status and changes in investigated symptoms.

CONCLUSION

Only a small proportion of women with symptomatic POP get worse within 5 years.

Cigarette smoking and adenocarcinomas of the esophagus and esophagogastric junction: a pooled analysis from the international BEACON consortium

BACKGROUND

Previous studies that showed an association between smoking and adenocarcinomas of the esophagus and esophagogastric junction were limited in their ability to assess differences by tumor site, sex, dose-response, and duration of cigarette smoking cessation.

METHODS

We used primary data from 10 population-based case-control studies and two cohort studies from the Barrett's Esophagus and Esophageal Adenocarcinoma Consortium. Analyses were restricted to white non-Hispanic men and women. Patients were classified as having esophageal adenocarcinoma (n = 1540), esophagogastric junctional adenocarcinoma (n = 1450), or a combination of both (all adenocarcinoma; n = 2990). Control subjects (n = 9453) were population based. Associations between pack-years of cigarette smoking and risks of adenocarcinomas were assessed, as well as their potential modification by sex and duration of smoking cessation. Study-specific odds ratios (ORs) estimated using multivariable logistic regression models, adjusted for age, sex, body mass index, education, and gastroesophageal reflux, were pooled using a meta-analytic methodology to generate summary odds ratios. All statistical tests were two-sided.

RESULTS

The summary odds ratios demonstrated strong associations between cigarette smoking and esophageal adenocarcinoma (OR = 1.96, 95% confidence interval [CI] = 1.64 to 2.34), esophagogastric junctional adenocarcinoma (OR = 2.18, 95% CI = 1.84 to 2.58), and all adenocarcinoma (OR = 2.08, 95% CI = 1.83 to 2.37). In addition, there was a strong dose-response association between pack-years of cigarette smoking and each outcome (P < .001). Compared with current smokers, longer smoking cessation was associated with a decreased risk of all adenocarcinoma after adjusting for pack-years (<10 years of smoking cessation: OR = 0.82, 95% CI = 0.60 to 1.13; and > or =10 years of smoking cessation: OR = 0.71, 95% CI = 0.56 to 0.89). Sex-specific summary odds ratios were similar.

CONCLUSIONS

Cigarette smoking is associated with increased risks of adenocarcinomas of the esophagus and esophagogastric junction in white men and women; compared with current smoking, smoking cessation was associated with reduced risks.

Dietary quercetin intake and risk of gastric cancer: results from a population-based study in Sweden

BACKGROUND

To study the impact of the dietary antioxidant quercetin on risk of gastric adenocarcinoma.

PATIENTS AND METHODS

Using data from a large Swedish population-based case-control study of gastric cancer (505 cases and 1116 controls), we studied the association between quercetin and risk of anatomic (cardia/noncardia) and histological (intestinal and diffuse) subtypes of gastric cancer.

RESULTS

We found strong inverse associations between quercetin and the risk of noncardia gastric adenocarcinoma, with an adjusted odds ratio (OR) of 0.57 (95% confidence interval 0.40-0.83) for the highest quintile (≥11.9 mg) of daily quercetin intake relative to the lowest quintile of intake (<4 mg quercetin/day), supported by a significant decreasing linear trend (P value < 0.001). Similar findings were observed for the intestinal and diffuse subtype. For cardia cancer, we found a less evident and nonsignificant inverse relationship. The protection of quercetin appeared to be stronger among female smokers, with the OR leveled of at values <0.2 in quintiles 3-5 (>6 mg quercetin/day).

CONCLUSIONS

High dietary quercetin intake is inversely related to the risk of noncardia gastric adenocarcinoma, and the protection appears to be particularly strong for women exposed to oxidative stress, such as tobacco smoking.

Interactive voice response and web-based questionnaires for population-based infectious disease reporting

The authors aimed to evaluate the web and an Interactive Voice Response (IVR) phone service as vehicles in population-based infectious disease surveillance. Fourteen thousand subjects were randomly selected from the Swedish population register and asked to prospectively report all respiratory tract infections, including Influenza-like Illness (ILI-clinical symptoms indicative of influenza but no laboratory confirmation), immediately as they occurred during a 36-week period starting October 2007. Participants were classified as belonging to the web or IVR group based on their choice of technology for initial registration. In all, 1,297 individuals registered via IVR while 2,044 chose the web. The latter were more often young and well-educated than those registered via IVR. Overall, 52% of the participants reported at least one infection episode. The risk of an infectious disease report was 14% (95% CI: 6, 22%) higher in the web group than in the IVR group. For ILI the excess was 27% (95% CI: 11, 47%). After adjustments for socio-demographic factors, statistically non-significant excesses of 1 and 8% remained, indicating trivial differences potentially attributable to the two reporting techniques. With attention to confounding, it should be possible to combine the web and IVR for simple reporting of infectious disease symptoms.

Duration of red blood cell storage and survival of transfused patients (CME)

BACKGROUND

Disquieting reports of increased complication and death rates after transfusions of red blood cells (RBCs) stored for more than 14 days prompted us to perform an observational retrospective cohort study of mortality in relation to storage time.

STUDY DESIGN AND METHODS

We conducted a cohort study utilizing data on all recipients of at least one RBC transfusion in Sweden and Denmark between 1995 and 2002, as recorded in the Scandinavian Donations and Transfusions (SCANDAT) database. Relative risks of death in relation to storage time were estimated using Cox regression, adjusted for several possible confounding factors.

RESULTS

After various exclusions, 404,959 transfusion episodes remained for analysis. The 7-day risk of death was similar in all exposure groups, but a tendency for a higher risk emerged among recipients of blood stored for 30 to 42 days (hazard ratio, 1.05; 95% confidence interval [CI], 0.97-1.12), compared to recipients of blood stored for 10 to 19 days. With 2-year follow-up, this excess remained at the same level (hazard ratio, 1.05; 95% CI, 1.02-1.08). No dose-response pattern was revealed and no differential effect was seen when the analyses were restricted to recipients of leukoreduced units only.

CONCLUSION

Although a small excess mortality was noted in recipients of the oldest RBCs, the risk pattern was more consistent with weak confounding than with an effect of the momentary exposure to stored RBCs. It seems, thus, that any excess mortality conferred by older RBCs in the combined Swedish and Danish transfusion recipient population is likely less than 5%, which is considerably smaller than in the hitherto largest investigation.

Nonobstetric risk factors for symptomatic pelvic organ prolapse

OBJECTIVE

To identify possible nonobstetric risk factors for symptomatic pelvic organ prolapse in the general female population.

METHODS

This was a population-based, cross-sectional study derived from a sample of 5,489 Stockholm women, 30 to 79 years old, who answered a validated questionnaire for the identification of symptomatic prolapse. The 454 women whose answers indicated the presence of such prolapse and the 405 randomly selected control participants with answers that gave no indication of prolapse received a 72-item questionnaire, which probed into a priori suspected risk factors. Only those women with intact uteri and no prior surgery for incontinence or prolapse were included. Multivariable logistic regression models estimated prevalence odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

In addition to age and parity, overweight (prevalence OR for body mass index [kg/m] 26-30 compared with 19-25 was 1.9, 95% CI 1.2-3.1), history of conditions suggestive of deficient connective tissue (varicose veins/hernia/hemorrhoids, prevalence OR for positive history compared with no history 1.8, 95% CI 1.2-2.8), family history of prolapse (prevalence OR for positive history compared with no history 3.3, 95% CI 1.7-6.4), heavy lifting at work (prevalence OR for 10 kg or more compared with no heavy lifting 2.0, 95% CI 1.1-3.6), and presence of constipation, hard stools, or difficult evacuation (prevalence OR relative to normal bowel habits 2.1, 95% CI 1.4-3.3) all were linked independently, significantly, and positively to the presence of symptomatic prolapse.

CONCLUSION

In this nonconsulting population, age and parity were the dominating risk factors, but significant independent associations with markers suggestive of congenital susceptibility (family history and conditions signaling weak connective tissue) and nonobstetric strain on the pelvic floor (overweight/obesity, heavy lifting, and constipation) imply that individual predisposition and lifestyle/environment also may play an important role. The causal direction of the association with bowel habits remains uncertain, and the link to family history could be partly because of information bias.

Interleukin 1-beta gene polymorphisms and risk of gastric cancer in Sweden

OBJECTIVE

Helicobacter pylori (H. pylori) infection stimulates the production of interleukin (IL)-1 beta, a pro-inflammatory cytokine and suppressor of gastric acid secretion. As both inflammation and hypochlorhydria, which might facilitate proximal colonization of H. pylori and other bacterial species alike, have been implicated in gastric carcinogenesis, much attention has been directed to functional genetic polymorphisms that affect the production of IL-1 beta. The purpose of this study was to clarify the role of these polymorphisms.

MATERIAL AND METHODS

We analysed a population-based, case-control study in 5 Swedish counties and a hospital-based, case-control study conducted in 8 Swedish hospitals, with a total of 351 gastric cancer cases and 539 controls. The IL1B-31, IL1B-511 and IL1B+3954 biallelic polymorphisms were genotyped using pyrosequencing. The variable number of tandem repeats (VNTR) polymorphism of IL1-RN was analysed using polymerase chain reaction (PCR) followed by gel electrophoresis. Relative risks were estimated by odds ratios with 95% confidence intervals, derived from unconditional logistic regression.

RESULTS

The risk of gastric cancer was unrelated to genotype in all of the studied polymorphic loci, and the absence of any association was confirmed in both the population-based and hospital-based case-control studies. Analyses confined to histological subtypes (intestinal or diffuse) and site-specific tumours (cardia or distal stomach), as well as analyses stratified by H. pylori infection status and family history of gastric cancer, did not reveal any significant increases or decreases in risk.

CONCLUSION

Our results do not lend support to the hypothesis that human genetic polymorphisms related to the production of IL-1 beta are associated with the risk of gastric cancer.

Measures of physical activity and their correlates: the Swedish National March Cohort

We compared the results of self-estimates of physical activity obtained with a novel instrument (the Energy Expenditure Questionnaire, EEQ) to those obtained from questions typically asked in epidemiological investigations (reference method) in a cohort of 42,150 Swedish men and women, aged 18-94. In the EEQ, participants were asked to report total physical activity by estimating the total time during a typical day and night spent on different physical activity intensity levels from the lowest (corresponding to lying in bed, 0.9 Metabolic Energy Turnover; MET) to the highest, (exceeding the intensity of to shovelling snow by hand, i.e., >6 MET). As a comparison, they also estimated hours per week devoted to household chores, commuting and leisure time physical activities classified as; light, moderate and heavy. The average physical activity estimated with the EEQ was 1.36 MET or 32.6 METh/day or 2,341 kcal/day. In comparison, physical activity estimated with the reference method represented no more than 17% of this amount. The Spearman's correlation coefficient between the two measures was 0.26. Using EEQ, men reported significantly more physical activity than women (mean = 36.3 vs. 30.6 METh/day). Body mass index (BMI) > or = 25, education > or = 12 years, and age > or = 60 years were significantly associated with lower physical activity. Questions focusing on leisure time exercise and a few other selected activities provide estimates of activity that correlate poorly with self-reported total energy output from all physical activity and inactivity. Investigators need to be more explicit about which component of activity they investigate.