Risk factors for Alzheimer's disease: a population-based, longitudinal study in Manitoba, Canada.

BACKGROUND: Current knowledge of risk factors for Alzheimer's disease (AD) is limited. Data from a longitudinal, population-based study of dementia in Manitoba, Canada were used to investigate risk factors for AD. METHODS: Cognitively intact subjects completed a risk factor questionnaire assessing sociodemographic, genetic, environmental, medical and lifestyle exposures. Five years later, 36 subjects had developed AD and 658 remained cognitively intact. RESULTS: Older subjects or those who had fewer years of education were at greater risk of AD. After adjusting for age, education and sex, occupational exposure to fumigants/ defoliants was a significant risk factor for AD (relative risk [RR] = 4.35; 95% CI : 1.05--17.90). A history of migraines increased the risk of AD (RR = 3.49; 95% CI : 1.39--8.77); an even stronger effect was noted among women. Self-reported memory loss at baseline was associated with subsequent development of AD (RR = 5.15; 95% CI : 2.36--11.27). Vaccinations and occupational exposure to excessive noise reduced the risk of AD. CONCLUSIONS: Some well-known risk factors for AD were confirmed in this study and potential new risk factors were identified. The association of AD with a history of migraines and occupational exposure to defoliants/fumigants is of particular interest because these are biologically plausible risk factors.     

Mortality and cataract: findings from a population-based longitudinal study.

The study was carried out in a rural population in central India. A random sample of 11 village communities provided 1020 persons aged 40-64 years, who were examined in 1982 and again reassessed in 1986. Statistical analysis, based on the Mantel-Haenszel method for stratified data, showed increased mortality in persons who had central lens opacities, compared with those who had trivial or no central lens opacities. The significant age-adjusted death ratio was just over 2 (2.2), as were the age/sex-adjusted and age/vision-adjusted estimates, which indicate doubling of mortality in the cataract cohort. Multiple regression analysis using the Cox proportional-hazards model gave very similar results. Statistical tests for homogeneity of death ratios across the various age/sex/vision strata were carried out, and the observed association between cataract and mortality was found to be consistent, both in males and in females, in the youngest and oldest age groups, and among those with adequate vision of 6/18 or better as well as among persons with serious visual impairment. There were no known diabetics in the study sample, which came from what could reasonably be regarded as a non-diabetic population.     

Bodyweight, gender, and quality of life: a population-based longitudinal study

Purpose

The objective of the paper is to describe trajectories of health-related quality of life (HRQL) associated with categories of body mass index (BMI): underweight, normal weight, overweight, obese class I, and obese classes II and III.

Methods

Data come from the longitudinal Canadian National Population Health Survey. Analyses are based on data for 3,864 men and 4,745 women who were 40+ in 1998/1999 and followed through 2006/2007. HRQL was measured with the Health Utilities Index Mark 3. Multi-level growth modeling was used.

Results

HRQL declined with age. For men, there was a large HRQL decrement for being underweight; trajectories for all other BMI categories were very similar. For women being underweight was associated with higher HRQL at younger ages but lower at older ages. Otherwise, for women, HRQL was ordered from highest to lowest: normal, overweight, obese class I, and obese classes II and III.

Conclusions

Given that excess weight is a risk factor for mortality and the development of chronic conditions, the HRQL results for men are surprising. The HRQL results for women may reflect both the importance of body image on mental health and the health effects of excess weight.     

Family size, day-care attendance, and breastfeeding in relation to the incidence of childhood asthma

A hypothesis has been suggested stating that children exposed early to infections are less likely to develop atopy or asthma. The authors investigated the relation between risk of childhood asthma and number of siblings as well as day-care attendance, as factors possibly increasing the likelihood of early infections, and breastfeeding as a factor reducing them. A case-control study was carried out in Montréal, Canada, between 1988 and 1995 that included 457 children diagnosed with asthma at 3--4 years of age and 457 healthy controls. Cases followed for 6 years were later classified as persistent or transient by the symptoms and use of medication after diagnosis. Among cases diagnosed at 3--4 years of age, the adjusted odds ratio for asthma was 0.54 (95% confidence interval (CI): 0.36, 0.80) for one sibling and 0.49 (95% CI: 0.30, 0.81) for two or more. The adjusted odds ratio for day-care attendance before 1 year of age was 0.59 (95% CI: 0.40, 0.87). Results were similar with persistent cases. Among transient cases (who possibly had an infection with wheezing at 3--4 years of age), day-care attendance and a short duration of breastfeeding resulted in increased risk. The results support the hypothesis that opportunity for early infections reduces the risk of asthma.     

Cannabis use and psychosis: a longitudinal population-based study

Cannabis use may increase the risk of psychotic disorders and result in a poor prognosis for those with an established vulnerability to psychosis. A 3-year follow-up (1997-1999) is reported of a general population of 4,045 psychosis-free persons and of 59 subjects in the Netherlands with a baseline diagnosis of psychotic disorder. Substance use was assessed at baseline, 1-year follow-up, and 3-year follow-up. Baseline cannabis use predicted the presence at follow-up of any level of psychotic symptoms (adjusted odds ratio (OR) = 2.76, 95% confidence interval (CI): 1.18, 6.47), as well as a severe level of psychotic symptoms (OR = 24.17, 95% CI: 5.44, 107.46), and clinician assessment of the need for care for psychotic symptoms (OR = 12.01, 95% CI: 2.24, 64.34). The effect of baseline cannabis use was stronger than the effect at 1-year and 3-year follow-up, and more than 50% of the psychosis diagnoses could be attributed to cannabis use. On the additive scale, the effect of cannabis use was much stronger in those with a baseline diagnosis of psychotic disorder (risk difference, 54.7%) than in those without (risk difference, 2.2%; p for interaction = 0.001). Results confirm previous suggestions that cannabis use increases the risk of both the incidence of psychosis in psychosis-free persons and a poor prognosis for those with an established vulnerability to psychotic disorder.     

Hearing, mobility, and pain predict mortality: a longitudinal population-based study

ObjectiveMeasures of health-related quality of life (HRQL), including the Health Utilities Index Mark 3 (HUI3) are predictive of mortality. HUI3 includes eight attributes, vision, hearing, speech, ambulation, dexterity, cognition, emotion, and pain and discomfort, with five or six levels per attribute that vary from no to severe disability. This study examined associations between individual HUI3 attributes and mortality.Study Design and SettingBaseline data and 12 years of follow-up data from a closed longitudinal cohort study, the 1994/95 Canadian National Population Health Survey, consisting of 12,375 women and men aged 18 and older. A priori hypotheses were that ambulation, cognition, emotion, and pain would predict mortality. Cox proportional hazards regression models were applied controlling for standard determinants of health and risk factors.ResultsSingle-attribute utility scores for ambulation (hazard ratio [HR] = 0.10; 0.04–0.22), hearing (HR = 0.18; 0.06–0.57), and pain (HR = 0.53; 0.29–0.96) were statistically significantly associated with an increased risk of mortality; ambulation and hearing were predictive for the 60+ cohort.ConclusionFew studies have identified hearing or pain as risk factors for mortality. This study is innovative because it identifies specific components of HRQL that predict mortality. Further research is needed to understand better the mechanisms through which deficits in hearing and pain affect mortality risks.     

Changes in alcohol intake and mortality: a longitudinal population-based study

BACKGROUND: Using alcohol intake at one point in time, numerous studies have shown a J- or U-shaped relation with all-cause mortality. Mortality is lowest among the light to moderate drinkers, with the risk of dying from coronary heart disease higher among nondrinkers and the risk of dying from cancer higher among heavy drinkers. We studied whether changes in individual alcohol intake result in corresponding changes in mortality. METHODS: In a longitudinal study of 6644 men and 8010 women, age 25 to 98 years, who had attended at least 2 health surveys with a 5-year interval between them, we addressed the risk of death after combinations of changes in alcohol intake. RESULTS: Mortality after changes in alcohol intake was consistent with the mortality observed among those who reported stable drinking. Stable drinkers showed a U-shaped all-cause mortality, with relative risks of 1.29 (95% confidence interval [CI] = 1.13-1.48) for nondrinkers (< 1 drink per week) and 1.32 (1.15-1.53) for heavy drinkers (> 13 drinks per week) compared with light drinkers (1 to 6 drinks per week). For coronary heart disease mortality, stable nondrinkers had a relative risk of 1.32 (0.97-1.79) compared with stable light drinkers and those who had reduced their drinking from light to none increased their risk (1.40; 1.00-1.95), and those who had increased from nondrinking to light drinking reduced their relative risk ratio (0.71; 0.44-1.14). Cancer mortality was increased in all groups of heavy drinkers. CONCLUSION: Persons with stable patterns of light and moderate alcohol intake had the lowest all-cause mortality. Individual changes in alcohol intake were followed by corresponding changes in mortality.     

Temporal and regional trends in IUD insertion: a population-based study in Ontario, Canada

Background

Intrauterine device (IUD) use is low in Canada and declined between 1985 and 1995. This study examines temporal and regional trends in IUD insertion in Ontario, Canada, from 1996 to 2006.

Study Design

We used physician billing data to determine annual age-adjusted IUD insertion rates for women aged 15-55 years and proportions inserted by gynecologists and family physicians (FPs). We used small area variation statistics to analyze variation in rates across the province.

Results

Annual insertion rates followed a U-shaped distribution and were lowest in 2001 and highest in 2006. From 1996 to 2006, the proportion inserted by FPs fell from 38.2% to 31.6% (p<.001). In 2006, women in regions with the highest rates were twice as likely to have an IUD inserted as those in the lowest-rate regions.

Conclusions

IUD insertion rates began to increase in 2001, the year of introduction of the levonorgestrel-releasing intrauterine system. Regional variation in rates suggests that access is not equal across the province and that strategies to support FPs to insert IUDs may be important to ensure adequate access.     

Variations in physicians' hospitalization practices: a population-based study in Manitoba, Canada.

This paper uses claims data from a universal health care system to describe physicians' hospitalization styles after adjusting for case-mix characteristics of their primary patients. Patients were uniquely assigned to that physician (general or family practitioners, internist, general surgeon, or obstetrician/gynecologist) seen most frequently over each two two-year periods (1972-74 and 1974-76). Four indices were developed including: 1) percentage of primary patients hospitalized; 2) mean number of readmissions for such patients; 3) mean length of stay; and 4) total days of hospitalization per primary care patient (a summary measure combining the first three). Rates of admission, not length of stay, were shown to be strongly related to this summary measure. Marked variations in the hospitalization indices were observed across physicians; these variations cannot be explained by the health or sociodemographic characteristics of a physician's patients. Rural physicians practicing in areas with high bed-to-population ratios and low occupancy rates were particularly high users of hospitals. The economic implications of different practice styles are shown to be large; physicians who were high users of hospitals serve 27 per cent of the patients but their patients consume 42 per cent of the hospital days.     

Abortion and depression: a population-based longitudinal study of young women

AIM: Induced abortion is an experience shared by a large number of women in Norway, but we know little about the likely social or mental health-related implications of undergoing induced abortion. International studies suggest an increased risk of adverse outcomes such as depression, but many studies are weakened by poor design. One particular problem is the lack of control for confounding factors likely to increase the risk of both abortion and depression. The aim of the study was to investigate whether induced abortion was a risk factor for subsequent depression. METHODS: A representative sample of women from the normal population (n=768) was monitored between the ages of 15 and 27 years. Questions covered depression, induced abortion and childbirth, as well as sociodemographic variables, family relationships and a number of individual characteristics, such as schooling and occupational history and conduct problems. RESULTS: Young women who reported having had an abortion in their twenties were more likely to score above the cut-off point for depression (odds ratio (OR) 3.5; 95% confidence interval (CI) 2.0-6.1). Controlling for third variables reduced the association, but it remained significant (OR 2.9; 95% CI 1.7-5.6). There was no association between teenage abortion and subsequent depression. CONCLUSIONS: Young adult women who undergo induced abortion may be at increased risk for subsequent depression.     

Problems with the graduated frequency approach to measuring alcohol consumption: results from a pilot study in Toronto, Canada

Aims: To evaluate advantages and disadvantages of the graduatedfrequency (GF) approach, which asks about the frequency of alcoholconsumption at mutually exclusive quantity levels (i.e. 12 ormore drinks, at least eight drinks but less than 12, etc.). Methods: Telephone survey of 464 adults aged 18 and older inToronto, Canada, using random digit dialling and computer-assistedtelephone interviewing. Results: Respondents reported higher frequency and volume ofdrinking on the GF compared to overall and beverage-specificquantity–frequency type measures; however, at least 16%of GF responses included double counting on their frequencyestimates using the GF. When these cases were excluded or corrected,differences between the GF and quantity–frequency measuresmostly disappeared. The GF was superior to quantity–frequencymeasures for identifying heavy episodic drinkers. However, theGF had little advantage over the weekly recall method exceptfor identifying very infrequent (i.e. less often than twicea month) heavy drinkers. Conclusions: Because the GF has a highrate of response errors in terms of measuring frequency of alcoholconsumption, other combinations of measures, including alternatemeasures of heavy episodic drinking should be considered.     

Long-term benefits of full-day kindergarten: a longitudinal population-based study

In the first longitudinal, population-based study of full-day kindergarten (FDK) outcomes beyond primary school in Canada, we used linked administrative data to follow 15 kindergarten cohorts (n ranging from 112 to 736) up to grade 9. Provincial assessments conducted in grades 3, 7, and 8 and course marks and credits earned in grade 9 were compared between FDK and half-day kindergarten (HDK) students in both targeted and universal FDK programmes. Propensity score matched cohort and stepped-wedge designs allowed for stronger causal inferences than previous research on FDK. We found limited long-term benefits of FDK, specific to the type of programme, outcomes examined, and subpopulations. FDK programmes targeted at low-income areas showed long-term improvements in numeracy for lower income girls. Our results suggest that expectations for wide-ranging long-term academic benefits of FDK are unwarranted.     

Sex,age, deprivation and patterns in life expectancy in Quebec,Canada: a population-based study

Background  

Little research has evaluated disparities in life expectancy according to material deprivation taking into account differences across the lifespan between men and women. This study investigated age- and sex-specific life expectancy differentials related to area-level material deprivation for the province of Québec, Canada from 1989-2004.     

Obesity prognosis: a longitudinal study of children from the age of 6 months to 9 years

The development of body fatness and leanness is examined in an ongoing prospective nutrition and growth study. Individual skinfold thicknesses, relative weights, weight gains, activity levels, and caloric intakes were examined at seven ages between 6 months and 9 years. Changes in body fatness in this group of children provide evidence that the obese infant usually does not become the obese child. Weight gain in infancy is also a poor predictor of 9-year old obesity. Changes from obese to non-obese or lean are often not linear. There is evidence that impending or actual obesity begins at ages 6 to 9 years with some predictability provided as early as age 2 years for girls, age 3 years for boys.     

Patient-reported outcomes in melanoma survivors at 1, 3 and 5 years post-diagnosis: a population-based cross-sectional study

Quality of Life Research - There is a lack of population-based data describing patient reported outcomes (PROs) in melanoma survivors which could guide the development of interventions and...