Risk of kidney stones with surgical intervention in living kidney donors.

A kidney stone in a person with a solitary kidney requires urgent attention, which may result in surgical and/or hospital attention. We conducted a matched retrospective cohort study to determine if living kidney donors compared to healthy nondonors have a higher risk of: (i) kidney stones with surgical intervention, and (ii) hospital encounters for kidney stones. We reviewed all predonation charts for living kidney donations from 1992 to 2009 at five major transplant centers in Ontario, Canada, and linked this information to healthcare databases. We selected nondonors from the healthiest segment of the general population and matched 10 nondonors to every donor. Of the 2019 donors and 20 190 nondonors, none had evidence of kidney stones prior to cohort entry. Median follow-up time was 8.4 years (maximum 19.7 years; loss to follow-up <7%). There was no difference in the rate of kidney stones with surgical intervention in donors compared to nondonors (8.3 vs. 9.7 events/10 000 person-years; rate ratio 0.85; 95% confidence interval [CI] 0.47-1.53). Similarly there was no difference in the rate of hospital encounters for kidney stones (12.1 vs. 16.1 events/10 000 person-years; rate ratio 0.75; 95% CI 0.45-1.24). These interim results are reassuring for the safety of living kidney donation.

Allometric scaling of flow-mediated dilation: is it always helpful?

Flow-mediated dilation (FMD) is calculated as the greatest percent change in arterial diameter following an ischaemic challenge. This Traditional %FMD calculation is thought to have statistical bias towards baseline diameter (Dbase ), which is reduced by allometric scaling. This study examined whether allometric scaling FMD influenced the difference between a group of healthy young and older adults compared to the Traditional %FMD, and to determine whether a New (allometric) scaling %FMD improved the ability to obtain individually scaled FMD. Popliteal artery FMD was assessed in 18 young (26 ± 3 years) and 17 older adults (77 ± 5 years). 'Corrected' mean FMD was generated from a log-linked ANCOVA model. Individual %FMD was evaluated using three calculations: (1) Traditional %FMD calculation; (2) Atkinson (allometric) scaling %FMD (peak diameter (Dpeak)/(Dbasescalingexponent)); and (3) New scaling %FMD ((Dpeak-Dbase)/(Dbasescalingexponent)). Traditional %FMD was significantly larger in young (5·82 ± 2·58%) versus old (3·72 ± 1·26%). 'Corrected' FMD means (Y: 5·97 ± 2·12%; O: 3·98 ± 2·06%) were similar to Traditional %FMD; however, the logarithmic transformation prevents statistical interpretation of group differences. Individually scaled %FMD using the Atkinson scaling resulted in values that were corrected for variations in Dbase but that were twofold to threefold larger than those of the Traditional calculation. New scaling %FMD resulted in values that were similar to values expected (Y: 6·21 ± 2·75%; O: 3·98 ± 1·36%); however, it did not effectively correct for variation in Dbase . Recommendations regarding the advantages of allometrically scaling %FMD should be made with caution until research clearly establishes the benefits of this approach.

Is smoking associated with the risk of developing Alzheimer's disease? Results from three Canadian data sets.

PURPOSE: To determine whether smoking is associated with Alzheimer's disease (AD). METHODS: Analyses were conducted using three Canadian data sets: the University of Western Ontario Dementia Study (200 cases, 163 controls), the Canadian Study of Health and Aging (258 cases, 258 controls), and the patient database from the Clinic for Alzheimer Disease and Related Disorders at the Vancouver Hospital and Health Sciences Centre (566 cases, 277 controls). The association between smoking and AD was investigated using bivariate analyses and multiple logistic regression models adjusted for the potential confounders age, sex, educational level, family history of dementia, head injury, and hypertension. RESULTS: The results of bivariate analyses were inconsistent across the three data sets, with smoking status a significant protective factor, a significant risk factor, or not associated with AD. The results of multiple logistic regression models, however, were consistent: any association between smoking status and AD disappeared in all three data sets after adjustment for confounders. CONCLUSIONS: Smoking status was consistently not associated with AD across all three data sets after adjustment for confounders. Failure to adjust for relevant confounders may explain inconsistent reports of the influence of smoking on AD. Any protective effect of smoking may be limited to specific AD subtypes (e.g., early onset AD).

Occupational injuries and exposures among Canadian dentists: the results of a national survey.

OBJECTIVES: To measure the frequency of occupational exposures reported by dentists in Canada and to identify factors associated with occupational exposure. DESIGN: A national mailed survey of a stratified random sample of 6,444 dentists with three follow-up attempts. Weighted data were analyzed using t tests, analysis of variance, and multiple logistic regression. RESULTS: The response rate was approximately 66%. Occupational exposures, percutaneous injuries, and mucous membrane exposures in the last year were reported by 67%, 62%, and 29% of respondents, respectively. Fewer than 1% reported exposure to human immunodeficiency virus or hepatitis B virus (HBV). Respondents reported means of 1.5 mucous membrane and 3.0 percutaneous exposures per year. HBV immunization was reported by 91% of dentists, but of these 28% reported no post-immunization serology. Other reports of suboptimal compliance included use of a postexposure protocol by only 41% and HBV vaccination of all assistants or of hygienists by 74% and 77% of respondents, respectively. Factors associated with percutaneous exposure included non-use of postexposure protocol or puncture-proof containers for sharps disposal, treating > or =20 patients per day, and male gender. Risk factors for mucous membrane exposure included non-use of eye protection or masks. CONCLUSION: This study provides evidence of the protective effect of puncture-proof containers, eye protection, and masks and raises concerns related to HBV post-immunization serology and postexposure protocols. To reduce risk of infection, educational interventions are required to improve compliance with Universal Precautions, with emphasis on comprehensive HBV immunization and post-immunization serology, the use of barriers, puncture-proof containers for sharps disposal, and postexposure protocols.

A self-paced step test to predict aerobic fitness in older adults in the primary care clinic.

OBJECTIVES: To study the potential usefulness of a submaximal self-paced step test as a prediction of maximal aerobic capacity (VO2max) in older adults in the primary care setting. DESIGN: Data were collected during a prospective randomized study of an exercise program. SETTING: Four university family medical clinics in London, Ontario, Canada. PARTICIPANTS: A random sample of 240 healthy older (> or =65) men (n = 118) and women (n = 122) from four family medical clinics underwent self-paced step testing in the clinic with a family physician (n = 16), and step testing and a maximal exercise treadmill test with measurement of respired gases in an exercise laboratory. Testing was done in random order (clinic/laboratory) separated by 2 weeks and then repeated at 52 weeks, following introduction of an exercise program. Relationships between outcome variables were examined by Pearson correlation coefficients while prediction of VO2max was examined using multivariate regression analysis. Cross-validation with 30 age-matched hypertensive and 40 age-matched post-hip arthroplasty patients was used to test the accuracy of the predictive models. MEASUREMENTS: Measured VO2max, predicted VO2max, step test time, step test heart rate, body mass index (BMI), and O2 pulse. RESULTS: Two hundred women (n = 108) and men (n = 92) completed both the initial and 52-week assessments. Stepping time, heart rate, age, BMI, and O2 pulse were strongly associated with VO2max for both a normal and a fast step pace and were chosen to develop the predictive model. Normal step-pace correlation with VO2max (ml/kg/min) was no different (female 0.93: male 0.91) from fast pace (0.95:0.90) with no difference between clinic and laboratory measurement at baseline or 52 weeks. Cross-validation showed no significant difference from the main group using the predictive model. CONCLUSIONS: The self-paced step test is a safe and simple clinical instrument that strongly and reliably predicts VO2max, is sensitive to change, and is generalizable in the family practice setting among community-dwelling older adults differing in fitness and health status.

Compliance with recommended infection control procedures among Canadian dentists: results of a national survey.

OBJECTIVES: The objective of this study was to investigate compliance with recommended infection control (IC) practices by dentists in Canada in 1995. DESIGN: A mailed survey of a stratified random sample of dentists (N = 6444), with 3 follow-up attempts. Weighted analyses included multiple logistic regression to identify the best predictors of "excellent" compliance (18 items). RESULTS: The adjusted response rate was 66.4%. Respondents reported use of an IC manual (52%); postexposure protocol (41%); biologic monitoring of heat-sterilizers (71%); hepatitis B immunization of dentists (91%: of these 72% had post-immunization screening; natural immunity 3%) all hygienists (78%), and all other clinical staff (70%); handwashing (before treating patients 76%, after degloving 63%); always wearing gloves (95%); changing gloves after each patient (97%); masks (82%); protective eyewear (82%); protective uniform (48%); puncture-proof container for sharps (94%); recapping needles with scoop technique/device (60%); flushing waterlines (55%); heat-sterilizing handpieces (94%; after each patient 77%); high-volume suction (92%) and "excellent" compliance (6%). Significant predictors of "excellent compliance" included attending continuing education about IC (>/=10 hours, odds ratio [OR] = 6.3; 6-10 hours, OR = 3.3), treating 20 to 29 patients per day (OR = 2.8), being women (OR = 2.7), and population of city in which practice is located (>500,000, OR = 2.5). CONCLUSION: Improvements in IC are necessary in dental practice. The introduction of mandatory continuing education about IC may improve compliance with recommended IC procedures, which is important because of concerns related to transmission of bloodborne pathogens and drug-resistant microorganisms.

Randomized trial of partial zona dissection for male infertility.

OBJECTIVES: To compare IVF rates using partial zona dissection versus zona intact insemination in couples with male infertility. To analyze pregnancy rates relative to sperm characteristics, fertilization rates, and treatment. DESIGN: Randomized prospective comparison of fertilization in sibling oocytes. Transfer of the three best quality embryos from one or both treatments. SETTING: Department of Gynaecology and Reproductive Medicine, University Hospital, London, Ontario, Canada. PARTICIPANTS: Thirty-two couples undergoing IVF with a principal diagnosis of male infertility. INTERVENTION: Treatment with partial zona dissection. MAIN OUTCOME MEASURES: Fertilization and pregnancy. RESULTS: Fertilization rates were 26% and 9% after partial zona dissection and IVF, respectively. Polyspermy was < 1% in each treatment. There were five singleton pregnancies in 29 completed cycles, three in cycles with fertilization only by partial zona dissection and two in cycles with both partial zona dissection and IVF fertilization. There were no pregnancies after fertilization by IVF only. Stepwise logistic regression analysis indicated that pregnancy was related to partial zona dissection, initial sperm concentration, and total acrosin activity. CONCLUSION: Partial zona dissection was associated with minimal polyspermic fertilization and higher normal fertilization rates than sibling oocytes treated by modified IVF. Pregnancy occurred only after transfer of embryos from partial zona dissection or combined partial zona dissection and IVF.

Aerobic fitness in a population of independently living men and women aged 55-86 years.

PURPOSE: The purpose was to examine, for a subset of a large random survey of men and women, the age-related changes in the parameters of aerobic function, maximal oxygen consumption (VO2max), and ventilatory threshold (T(VE)). METHODS: A "ramp-like" treadmill protocol was designed to measure VO2max and T(VE) on a total of 298 subjects (152 men and 146 women), aged 55-86 yr. RESULTS: Data for VO2max (and HRmax) and T(VE) by 5-yr age groups provide "normative" results. Age-related declines in VO2max and T(VE) were fit by a linear model; however, age explained at most 37% of the variance across ages 55-86 yr. In this restricted age range, the rate of decline in VO2max, in both men (-0.034 L x min(-1) x yr(-1)) and women (-0.019 L x min(-1) x yr(-1)), was similar to that of previous reports for linear regression with age. Men, but not women, showed a decrease in body mass across age. Thus, the decline in VO2max expressed relative to body mass was similar in men (0.31 mL x kg(-1) x min(-1) x yr(-1)) and women (0.25); however, across this older age the decline is slower than noted for younger groups. The minimum level of aerobic power compatible with an independent life at age 85 yr was approximately 18 mL x kg(-1) x min(-1) in men and 15 mL x kg(-1) x min(-1) in women. Regression analysis showed HRmax across this age span is not well predicted by age. T(VE) across age declined at about one-half the rate of the VO2max, and in older age was approximately 85% of the VO2max. CONCLUSION: The study provides "normative" cardiorespiratory function data of a random sample of independently living men and women aged 55-86 yr.

Impact on postmenopausal symptoms of adding continuous C-21 versus C-19 progestin to estrogen.

OBJECTIVE: To compare the effects of (i) continuous low dosage C-19 progestin (dl-norgestrel, NG) plus cyclical conjugated estrogen (CEE) versus (ii) continuous low dosage C-21 progestin [medroxyprogesterone acetate (MPA)] plus CEE on postmenopausal vaginal bleeding, mood and somatic, psychosomatic and psychological symptoms. METHODS: Nine hypercholesterolemic postmenopausal women with intact uteri were randomly assigned in a prospective, double-blind, two-period cross-over study of CEE (25/28 days) plus either (i) NG, (0.05 mg/day) or (ii) MPA (2.5 mg/day) for 1 year and after an appropriate wash-out period were switched to the alternative regimen for another year. Four hysterectomized control subjects received the CEE only. RESULTS: Administration of CEE + MPA versus CEE + NG resulted in a significantly higher percent of cycles which were free of vaginal bleeding (97 vs 85%), spotting (92 vs 79%) and either spotting or bleeding (92 vs 76%, P < 0.01). All three regimens significantly reduced the overall combined scores for postmenopausal somatic, psychosomatic and psychological symptoms (P < 0.05). CONCLUSIONS: Vaginal bleeding and/or spotting were significantly less frequent with CEE + MPA versus CEE + NG. However, each of the three hormonal regimens improved mood and significantly reduced postmenopausal symptoms in comparison to untreated control values.

The effectiveness of an electro-ionizing toothbrush in the control of dentinal hypersensitivity.

The object of the investigation was to test the value of the 3M Brand Electro-Ionizing Toothbrush in the treatment of dentinal hypersensitivity. Eighty-eight volunteers were divided into three groups, each using different methods: (I) stannous fluoride dentifrice and 3M brush without a battery; (II) stannous fluoride dentifrice and 3M brush with a 1 1/2 volt battery; and (III) strontium chloride dentifrice and 3M brush without a battery. The volunteers brushed their teeth for 3 minutes twice a day for 12 weeks using one of the three test agents. The subjects were tested at weeks 0, 2, 4, 8 and 12 by means of a cold water spray quantitated by a temperature probe. All three groups experienced improvement and by week 12 Groups II and III displayed much less sensitivity than did Group I. At the end of the 12 weeks the subjects were questioned as to benefit of treatment. The questionnaire revealed that stannous fluoride with the ionizing brush provided significantly greater relief than did the stannous fluoride alone.

Stress-coping and other psychosocial risk factors: a model for smoking in grade 6 students.

Smoking uptake by adolescents is best studied by a following a cohort of children as they proceed through adolescence. In this analysis of the first stage of such a study, several hypotheses about psychosocial factors that may modify the initiation of smoking in adolescents were examined in 1,552 11- and 12-year-olds in a school system in Scarborough, Canada. Investigation of the stress-coping hypothesis and other possible effect modifiers as they relate to ever-smoking revealed that stress (measured by number of life events) was important for both males and females (p = .0163 and .0056, respectively). However, the mechanisms underlying smoking appear to be different for males and females, even at this young age. In models adjusting for several factors simultaneously, rebelliousness was found to be the most important factor (p = .0001) followed by attitudes toward the effect of second-hand smoke (p = .0063) for males, whereas for females, mother smoking was the most important factor (p = .0001) followed by rebelliousness (p = .0102). Implications for design of prevention programs are discussed.

Are psychosocial factors related to smoking in grade-6 students?

The associations of psychosocial characteristics with both gender and smoking behavior were explored in a sample of 1552 grade-six students from 107 schools in one Ontario, Canada, school district. Ever smokers were more likely to have spending money: a part-time job; to have missed school in previous 2 months; perceive themselves to be below average or average in school; to have a mother, a father, and a sibling who smoke; to have consumed low alcohol and alcoholic beverages; and agree with fewer positive statements concerning second-hand smoke and the addictive properties of smoking. Ever smokers had more close friends who tried smoking, spent more time with friends, scored higher on depression, rebelliousness, and social conformity scales, reported more life events in the past year, and had lower scores for social support. More boys than girls had ever smoked (18.9% vs. 14.7%). Gender differences were found for sociodemographic, attitudes, social bonding, and psychosocial factors.

The role of age- and population-based differences in the attitudes, knowledge and infection control practices of Canadian dentists.

OBJECTIVES: To investigate age- and population-based differences in dentists' infection control practices and willingness and refusal to treat patients with HIV. METHODS: A national mailed survey of a stratified random sample of dentists in Canada (n = 6444) with three follow-up attempts. Pearson's chi-square test and multiple logistic regression were used for data analysis. Predictor variables included population, age, gender, marital status, specialty, number of patients treated per day and continuing education on HIV/AIDS. RESULTS: The adjusted response rate was 66.4%. The best predictors of willingness to treat patients with HIV were younger age (compared with dentists > or = 60 years of age: < 30 years, OR = 8.6, 30-39, OR = 3.4; 40-49, OR = 2.7; 50-59, OR = 1.6), attending continuing education on HIV/AIDS in the past 2 years (> 10 hours, OR = 1.6 compared with zero hours), practicing in small population centres < 10,000 (OR = 1.6 compared with > 500,000) and gender (male OR = 1.3). The best predictors of refusal to treat patients with HIV were older age (compared with dentists < 30 years of age: > or = 60, OR = 6.1; 50-59, OR = 4.1; 40-49, OR = 3.0; 30-39, OR = 2.6); and practicing in population centres > 500,000 (OR = 1.5 compared with < 10,000). However, the latter group also reported treating more HIV patients than respondents in smaller communities. Infection control practices varied significantly with age and population centre. Dentists in communities of < 10,000 were more compliant with HBV vaccination, but less compliant with handwashing after degloving and the use of infection control manuals. Similarly, dentists > 60 years of age were the least compliant with HBV immunization, routine use of barriers and sterilization of handpieces, but reported the highest compliance with handwashing. CONCLUSIONS: Age- and population-based differences need to be considered in planning educational interventions to improve both access to care for patients with HIV and dentists' compliance with recommended infection control procedures.

Geographic differences in the attitudes, knowledge and infection control practices of Ontario dentists.

Geographic differences in the HIV related attitudes, knowledge and behaviours of 5,997 dentists in Ontario were investigated using mailed questionnaires (response rate 70%). Proportionately more respondents from larger population centres reported that they knowingly treated HIV-infected patients (p < 0.00001), they were unwilling to treat HIV-infected patients (p < 0.05), they had an exaggerated perception of the risk of HIV infection after a needlestick injury (p < 0.01), they were concerned about personal risk (p < 0.01) and staff fears (p < 0.05) related to HIV/AIDS, and that patients with HIV or AIDS should be treated in hospitals/specialized practices (p < 0.001). Multiple logistic regression analysis controlling for age, sex, and specialty, showed that respondents who practised in smaller population centres were significantly more willing to treat HIV-infected patients ( < 10,000, odds ratio = 1.6; 10,000-49,999, odds ratio = 1.3). Significantly fewer respondents in the Central West, and Central East Health Planning Region, where AIDS is most prevalent, reported that they were willing to treat HIV patients.

An outcome measure to quantify passive stiffness of the ankle.

The primary aim of this research project was to develop a method to quantify a specific variable of neuromuscular function, passive stiffness of the ankle. It was then used to determine if values for the outcome measure varied with age and sex in a sample of elderly men and women between 55 and 85 years old. Subjects were screened for medical conditions contraindicative to testing, e.g. severe arthritis, other history of bone or muscle disorders, ankle fracture, neural disorder causing spasticity or contracture. A rotatable footplate which recorded position and resistive torque with a potentiometer and strain gauge, respectively, was linked to an electric, computer-controlled torque motor. Passive elastic stiffness, defined as the slope of the passive resistance curve at 10 degrees dorsiflexion (in N.m/degree), was greater in males, (p < .001), and increased with age (p = .002). There was a significant effect of age group on passive range of motion (ROM) values for ankle dorsiflexion (p < .001), but also a significant sex by age interaction (p = .001). Females showed a large drop from a mean of 19.3 degrees +/- 3.2 in the youngest group (55-60 yr) to 12.1 degrees +/- 5.5 in the 81 to 85 yr olds. Corresponding mean values for the middle-aged males were 15.4 degrees +/- 4.3 versus 13.1 degrees +/- 3.5 of dorsiflexion in the group of 81 to 85 yr old men. It was concluded that passive ROM of the ankle into dorsiflexion showed decreases in the elderly, which seemed to reflect less complaint tissue structures.

Changes in dentists' infection control practices, knowledge, and attitudes about HIV over a 2-year period.

OBJECTIVE: To investigate changes in the infection control practices, attitudes, and knowledge of dentists as they relate to HIV/AIDS: STUDY DESIGN: A comparison of responses to surveys conducted in 1992 (n = 258) and 1994 (n = 262) with the use of univariate/multivariate analyses and McNemar's test for paired data. RESULTS: The response rate were > 70%. There were significant increases in reports of continuing education related to HIV/AIDS, heat sterilization of handpieces, use of masks, and knowledge of risk of HIV infection after a needlestick injury. Significantly fewer respondents reported concerns about staff fears about HIV/AIDS: Reports of willingness to treat patients with HIV increased from 68% to 77%. The best predictors of willingness to treat changed from primarily infection control variables to lack of concern with respect to risk or loss of patients when treating persons with HIV. CONCLUSIONS: Increased use of infection control procedures and knowledge may be partly attributable to the introduction of mandatory continuing education in 1993.

Nonresponse bias in a survey of Ontario dentists' infection control and attitudes concerning HIV.

OBJECTIVE: This study investigated late response and nonresponse bias in an HIV-related survey of dentists. METHODS: Questionnaires with ID numbers were mailed to all dentists in Ontario (N = 5,997) with additional mailings four and seven weeks later. RESULTS: Proportionately more respondents who returned questionnaires less than four weeks after the first mailing reported that they knowingly treated (P < .05) or were willing to treat HIV-infected patients (P < .05); that they had an accurate perception of risk of HIV infection after a needlestick injury (P < .01), and preferred not to refer HIV-infected patients (P < .01). Linear extrapolation of cumulative percent responses indicated nonresponse bias in terms of attitude and knowledge items; however, the magnitude was low. CONCLUSIONS: The effects of late response and nonresponse bias on the results of this study were small. However, these results cannot be generalized beyond the study population, and obtaining high response rates and testing for nonresponse bias in surveys of attitudes related to HIV are recommended.

Longitudinal tracking and retention in a school-based study on adolescent smoking: costs, variables, and smoking status.

Methods used to track a cohort of Grade 6 students through Grades 8 and 11, and costs involved for survey completion in school and by mail for ever and never smokers from the original group are detailed. At baseline, 1,598 students in Scarborough, Canada, completed a questionnaire on smoking, drinking, and health, and again in Grade 8 (N = 1,543/1,598) and Grade 11 (N = 1,454/1,598). In Grades 8 and 11, tracking and administering the questionnaire was more costly per participant when the survey was administered by mail than in school. Average completion costs were highest for Grade 11 students who used tobacco at baseline ($52.44). Students categorized as ever smokers in Grade 6 were harder to locate at each phase of testing, which suggests that this group should be identified at baseline so that closer tracking procedures may be employed between data collection points.

Obstetric conditions and the placental weight ratio.

INTRODUCTION: To elucidate how obstetric conditions are associated with atypical placental weight ratios (PWR)s in infants born: (a) ≥37 weeks gestation; (b) at ≥33 but <37 weeks gestation; and (c) <33 weeks gestation. METHODS: The study included all in-hospital singleton births in London, Ontario between June 1, 2006 and March 31, 2011. PWR was assessed as <10th or >90th percentile by gestational age-specific local population standards. Multivariable analysis was carried out using multinomial logistic regression with blockwise variable entry in order of temporality. RESULTS: Baseline factors and maternal obstetric conditions associated with PWR <10th percentile were: increasing maternal height, overweight and obese body mass indexes (BMI), large for gestational age infants, smoking, and gestational diabetes. Obstetric factors associated with PWR >90th percentile were: underweight, overweight and obese BMIs, smoking, preeclampsia, placenta previa, and placental abruption. In particular, indicators of hypoxia and altered placental function were generally associated with elevated PWR at all gestations. DISCUSSION: An association between obstetric conditions associated with fetal hypoxia and PWR ≥90th percentile was illustrated. CONCLUSIONS: The multivariable findings suggest that the PWR is similarly increased regardless of the etiology of the hypoxia.