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.

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.

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.

Influential observations in weighted analyses: examples from the National Longitudinal Survey of Children and Youth (NLSCY).

This paper highlights the impact of survey weights on model fit in multiple linear regression with specific reference to the National Longitudinal Survey of Children and Youth (NLSCY) and provides recommendations for the treatment of influential observations. Multiple linear regression was used to estimate the association between child and family factors in the preschool years and vocabulary development at school age. Analyses were performed with and without survey weights. The model fit was assessed by examining the distribution of the studentized residuals and the change in the regression coefficients that would occur if an observation were removed. Two summary measures of influence, Dffits and Cook's D are reported. The models were refit excluding influential observations. Weighting of the linear model resulted in previously non-influential observations having an undue influence on the estimation of the regression parameters in the weighted model. The influential observations were driven primarily by the size of the survey weight as opposed to unusual values of x and y. Researchers working with large national health surveys such as the NLSCY and the National Population Health Survey (NPHS) are advised to include a detailed influence analysis before any final conclusions are made.

Comprehensive tobacco control policies and the smoking behaviour of Canadian adults.

OBJECTIVE: To examine the associations of cigarette prices, restrictions on public smoking, and health education with the odds of adult smoking and amount smoked daily. DESIGN: Multi-level analysis of adult (age 25+) smoking patterns in Canada's National Population Health Survey, after adding administrative data on prices, bylaws, and health education according to the survey respondent's place of residence. SETTING/SUBJECTS: Population based sample of Canadians age 25+ in households (n = 14 355). OUTCOME MEASURES: Smoking status, amount consumed daily. ANALYSIS: Logistic regression for smoking status, multiple regression for amount smoked, with controls for age, education, marital status; separate analyses for men and women. RESULTS: Cigarette prices were positively associated with the odds of being a non-smoker and negatively with amount smoked, for adults of both sexes. Per capita health education expenditures were positively associated with the odds of being a non-smoker and negatively with amount smoked--for men but not women. The restrictiveness of municipal bylaws limiting public smoking was positively associated with the odds of being a non-smoker and negatively with amount smoked--for women but not men. These results are independent of age, education, and marital status. CONCLUSIONS: To be effective, tobacco control must comprise a mix of strategies as men and women respond differently to health education and restrictions on public smoking; taxation, reflected in higher cigarette prices, is the only one of these measures related to smoking for both sexes. This model permits calculations of the level of increase in each measure that is required to reduce the prevalence of smoking by a specified amount.

Lung function in older humans: the contribution of body composition, physical activity and smoking.

An allometric model was used to determine the important factors related to the decline in forced expiratory volume (FEV1.0) across ages 55-86 years in independently living men and women. Measurements were available from a randomized sample of 181 men and 203 women residing in London, Ontario, Canada. The effects of height, age, sex, adiposity, fat free mass (FFM), grip strength and physical activity (PA) on FEV1.0 were assessed using an allometric model to test the hypothesis that sex differences in lung function would be due in part to sex-related differences in the aforementioned variables and would therefore be eliminated by our analysis. The following model was linearized and parameters were identified using standard multiple regression: FEV1.0 = height(beta1) x FFM(beta2) x grip strength(beta3) x PA(beta4) x exp(beta0 + beta5age + beta6sex + beta7smoking + beta8%body fat) x epsilon. Results indicate that the amount of FFM and heavy intensity physical activity participated in by the elderly may be more important in influencing forced expiratory function than previously recognized. In addition, results from this study have confirmed the importance of age and height in the prediction of FEV1.0 and demonstrated a negative effect of smoking on lung function. Individuals with a greater FFM and physical activity level tended to be associated with an above average lung function performance. The cross-sectional rate of decline in FEV1.0 determined from our model was approximately 12% per decade.

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.

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).

Models of the relationship of stress, depression, and other psychosocial factors to smoking behavior: a comparison of a cohort of students in grades 6 and 8.

BACKGROUND: Six specific hypotheses regarding putative mechanisms by which stressful life events might lead to initiation of smoking among adolescents were proposed and tested on a Grade 6 cohort of students in Scarborough, Ontario, Canada. In addition, the data were used to determine the set of risk factors for initiation of smoking most pertinent to the experience of the cohort. METHODS: The same relationships were examined for the 1,543 students when they were in Grade 8 and compared to the earlier Grade 6 results. The hypotheses include the effects of personal resources (coping, self-esteem, social support, and mastery), social conformity, rebelliousness, attitudes, smoking environment factors, and gender differences. RESULTS: The hypotheses were not unequivocally supported, except for the hypotheses about attitudes and smoking environment as well as gender effects. Males and females differ with regard to the variables and interrelationships in both years and in the final models developed. In Grade 6, there are more smoking environment items for males than for females. By Grade 8, male smoking is influenced by mastery, social conformity, and rebelliousness, while for females environmental smoking and rebelliousness are important. CONCLUSION: Male and female students differ in how stress, depression, and smoking are related in the presence of psychosocial factors.

Does an interaction between smoking and drinking influence the risk of Alzheimer's disease? Results from three Canadian data sets.

Investigation of the relationship of smoking and drinking to Alzheimer's disease (AD) may advance research on the cause of AD and provide a basis for treatment. Pharmacological mechanisms for an involvement of smoking and drinking are plausible but epidemiologic reports are inconsistent. Evidence of behavioural and physiological interactions suggests that tobacco and alcohol use may not only individually affect AD, but may also modify each other's effects. A modelling strategy was developed to examine the interaction between smoking and drinking on the risk of AD. Three Canadian data sets were analysed: the University of Western Ontario Dementia Study (UWODS) (n=363); the Canadian Study of Health and Aging (CSHA) (n=516), and the database from the Clinic for Alzheimer Disease and Related Disorders at the Vancouver Hospital and Health Sciences Centre, University of British Columbia site (UBC) (n=843). Multiple logistic regression models were adjusted for the potential confounders age, age squared, sex, education, family history of dementia, head injury and hypertension. Analysis of the CSHA provided evidence consistent with the hypothesis that smoking and drinking influence each other's effects on AD, with smoking reducing the risk of AD among drinkers. A similar interaction was marginally significant (p=0.052) in the UWODS data set, but not significant in the UBC data. Extension of these analyses, particularly in longitudinal studies and within genetic risk groups, is needed to determine whether this interaction can be replicated. If so, research on the biological interactions of nicotine and alcohol may provide a basis for the development of therapeutic interventions as well as providing clues to the cause of this disorder.

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.

Interval estimation for Cohen's kappa as a measure of agreement.

Cohen's kappa statistic is a very well known measure of agreement between two raters with respect to a dichotomous outcome. Several expressions for its asymptotic variance have been derived and the normal approximation to its distribution has been used to construct confidence intervals. However, information on the accuracy of these normal-approximation confidence intervals is not comprehensive. Under the common correlation model for dichotomous data, we evaluate 95 per cent lower confidence bounds constructed using four asymptotic variance expressions. Exact computation, rather than simulation is employed. Specific conditions under which the use of asymptotic variance formulae is reasonable are determined.

Modelling the influence of fat-free mass and physical activity on the decline in maximal oxygen uptake with age in older humans.

The purpose of this study was to use an allometric model (maximal oxygen uptake (VO2,max) = FFMbeta1 x PAbeta2 x exp(beta0 + beta3 age + beta4 sex) x epsilon) to determine the influence of fat-free mass (FFM), physical activity (PA), sex and age on VO2,max in older men (n = 152) and women (n = 146) aged 55-86 years. VO2,max was measured during a fatigue-limited treadmill test, FFM was determined from skinfold thickness and physical activity by the Minnesota Leisure Time Physical Activity questionnaire. The model was linearised by taking the natural logarithm of VO2,max, FFM and physical activity. Variables were selected using multiple linear regression (P < 0.05). The sex variable was not significant (P = 0.062). The model explained 72.1% of the variance in VO2,max. Significant individual coefficients were incorporated into the model yielding the following expression: VO2,max = FFM0.971 x PA0.026 x exp(-2.48-0.015age). Therefore, FFM and physical activity were significant factors contributing to the changes in VO2,max with age. In addition, controlling for FFM and physical activity abolished sex differences in VO2,max. The rate of decline in VO2,max (after accounting for FFM and physical activity) with age, was approximately 15% per decade.

Modelling the influence of age, body size and sex on maximum oxygen uptake in older humans.

The purpose of this study was to describe the influence of body size and sex on the decline in maximum oxygen uptake (O2,max) in older men and women. A stratified random sample of 152 men and 146 women, aged 55-86 years, was drawn from the study population. Influence of age on O2,max, independent of differences in body mass (BM) or fat-free mass (FFM), was investigated using the following allometric model: O2,max = BMb (or FFMb) exp(a + (c ' age) + (d ' sex)) [epsilon]. The model was linearised and parameters identified using standard multiple regression. The BM model explained 68.8 % of the variance in O2,max. The parameters (+/- s.e.e., standard error of the estimate) for lnBM (0.563 +/- 0.070), age (-0.0154 +/- 0.0012), sex (0.242 +/- 0.024) and the intercept (-1.09 +/- 0.32) were all significant (P < 0.001). The FFM model explained 69.3 % of the variance in O2,max, and the parameters (+/- s.e.e) lnFFM (0.772 +/- 0.090), age (-0.0159 +/- 0.0012) and the intercept (-1.57 +/- 0.36) were significant (P < 0.001), while sex (0.077 +/- 0.038) was significant at P = 0.0497. Regardless of the model used, the age-associated decline was similar, with a relative decline of 15 % per decade (0.984 exp(age)) in O2,max in older humans being estimated. The study has demonstrated that, for a randomly drawn sample, the age-related loss in O2,max is determined, in part, by the loss of fat-free body mass. When this factor is accounted for, the loss of O2,max across age is similar in older men and women.

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.

Physician contact with older community patients: is there an association with physical fitness?

BACKGROUND: Contact with family physicians by older adults may be linked to their physical fitness in addition to other health, behavioral, and sociodemographic determinants. We studied a stratified random sample of urban community-dwelling elderly patients in London, Ontario, Canada, to describe the interaction of physical fitness measures and a number of health and lifestyle behaviors and sociodemographic outcomes with family physician contact over 1 year. We hypothesized that physician contact would be associated with lower indices of physical fitness and that association would be similar to other known determinants of physician utilization. METHODS: Three hundred seventy-five noninstitutionalized elderly men (N = 185) and women (N = 190) ages 55 to 84 years were recruited from the municipal tax assessment list for the city of London (population 280,000). Four categories of independent variables were selected to reflect common determinants of health (physical fitness, self-reported and clinically measured health, lifestyle behaviors, and sociodemographics). The association between these categories of variables and self-reported contact with family physicians and a variety of health professionals was determined for the year prior to the study. RESULTS: Forty-six percent of the subjects had at least one physician contact in the month prior to the study and 79% within the previous year. None of the other health professions (including nursing, chiropractic, physiotherapy, homemaking, and dentistry) were contacted more than once in the previous year. Lifestyle and sociodemographic variables including activity habits, smoking, income, marital status, and education were not associated with physician contact, whereas poor self-reported cardiovascular health and use of cardiovascular and pulmonary medications were associated with physician contact. Interestingly, physical fitness variables including maximal aerobic capacity, grip strength, and hip flexibility were not associated with physician contact. CONCLUSIONS: The absence of an association among physical fitness, lifestyle, and sociodemographic variables and physician contact was not anticipated and may be due to the selection of individuals who were independent, active community dwellers. It may be that most of the physician contact in this relatively healthy and physically fit sample was preventive in nature, for example, monitoring common chronic disease states in the elderly including cardiovascular and pulmonary disease. This paper reports baseline data from a longitudinal study of the interaction between physical fitness and health outcomes in groups of older community-dwelling individuals. As this group ages further, it would be interesting to determine the use of the health care system in relation to their changing functional and health status. In particular, do chronic health conditions such as cardiovascular disease, which increase in prevalence with age, become modified through maintenance of physical fitness and does this impact on health service use?

Infection control practices across Canada: do dentists follow the recommendations?

This study investigated provincial and territorial differences in dentists' compliance with recommended infection control practices in Canada (1995). Questionnaires were mailed to a stratified random sample of 6,444 dentists, of whom 66.4% responded. Weighted analyses included Pearson's chi-square test and multiple logistic regression. Significant provincial and territorial differences included testing for immune response after hepatitis B virus (HBV) vaccination, HBV vaccination for all clinical staff, use of infection control manuals and post-exposure protocols, biological monitoring of heat sterilizers, handwashing before treating patients, using gloves and changing them after each patient, heat-sterilizing handpieces between patients, and using masks and uniforms to protect against splatter of blood and saliva. Excellent compliance (compliance with a combination of 18 recommended infection control procedures) ranged from 0% to 10%; the best predictors were more hours of continuing education on infection control in the last two years, practice location in larger cities (> 500,000) and sex (female). Clearly, improvements in infection control are desirable for dentists in all provinces and territories. Extending mandatory continuing education initiatives to include infection control may promote better compliance with current recommendations.

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.