Epidemiology of pertussis in Alberta, Canada 2004-2015.

BACKGROUND: We describe the epidemiology of pertussis in Alberta, Canada by person, place, and time between 2004 and 2015, identify outbreak years, and examine vaccination coverage and vaccination timeliness. METHODS: We used health data from Alberta's Communicable Disease Registry System for the period of January 1, 2004 through August 31, 2015 to identify unique cases of pertussis. Unique cases were deterministically linked to data in Alberta's immunization repository and health care insurance plan registry. Population estimates and vaccination coverage were extracted from Alberta's online Interactive Health Data Application. We estimated pertussis incidence rates per 100,000 persons by year, age group, gender, and health zone. Outbreak years were identified using a one-sided cumulative sum (CUSUM) analysis by comparing annual incidence rates to baseline rates. RESULTS: Over the period, 3510 cases of pertussis were confirmed by laboratory testing or epidemiological linkage. Incidence rates per 100,000 persons were highest in 2004 (20.5), 2005 (13.6), and 2015 (10.4) for all age groups. Incidence rates were highest among the youngest age groups and decreased as age groups increased. Based on CUSUM analysis, 2008 and 2012 met the criteria for outbreak years. Vaccination coverage was over 90% among the general population, however only 61% of cases received at least one dose. About 60% of cases were diagnosed 5+ years after receiving the vaccine. Approximately 87-91% of vaccinated cases did not receive the first three vaccine doses in a timely manner. CONCLUSION: Pertussis incidence rates fluctuated over the period across all age groups. The majority of cases had no record of vaccination or were delayed in receiving vaccines. CUSUM analysis was an effective method for identifying outbreaks.

Impact of a 3-year multi-centre community-based intervention on risk factors for chronic disease and obesity among free-living adults: the Healthy Alberta Communities study.

BACKGROUND: Healthy Alberta Communities (HAC) was a 3-year community-based intervention to reduce lifestyle-related risk factors for chronic disease and obesity at a population-level. The current paper examines changes in blood pressure (BP) and anthropometric indicators within HAC communities compared to secular trends. METHODS: Between 2006 and 2009, this community-academic partnership sought to create environments supportive of healthier dietary and physical activity behaviours within four diverse communities in Alberta, Canada. Height, weight, waist and hip circumference and BP were measured among 1554 and 1808 community residents at baseline (2006) and follow-up (2009), respectively. A comparison sample was drawn from a representative national survey. Samples were stratified by age and change between pre- and post-intervention was assessed using t-tests. Changes in parameters over time between groups were compared using meta-analysis. The net difference in change in outcomes (change in intervention communities minus change in comparison group) represented the effect of the intervention. RESULTS: Adjusted systolic (SBP) and diastolic (DBP) BP declined within most age groups in HAC communities from pre- to post-intervention. The net decline in SBP was 1 mmHg in 20-39 year olds (p = 0.006) and 2 mmHg in 40-59 year olds (p = 0.001), while the net decline in DBP was 3 mmHg in 20-39 year olds (p < 0.001), 2 mmHg in 40-59 year olds (p < 0.001) and 3 mmHg in 60-79 year olds (p < 0.001). The net increase in the proportion of individuals with normal BP was 5.9 % (p < 0.001), while the net decline in the proportion of individuals with stage 1 hypertension was 4.5 % (p < 0.001). BMI and body weight were unchanged. There was a significant net increase in waist and hip circumference among 20-39 year olds within intervention communities. CONCLUSIONS: Findings suggest HAC succeeded in shifting the population distribution of BP in a leftward direction. By contrast, anthropometric parameters remained unchanged or worsened within intervention communities. Therefore, while improvements in some clinical risk factors can be achieved through relatively diffuse and shorter-term community-level environmental changes, improvements in others may require interventions of greater intensity and duration. Evaluating the success of community-based interventions based on their efficacy in changing individual-level clinical indicators may, however, underestimate their potential.

Multiple Sclerosis Mortality Rates in Canada, 1975-2009.

BACKGROUND: This study examined mortality due to multiple sclerosis (MS) in Canada, 1975-2009 to determine whether there has been a change in age at death relative to the general population and decrease in MS mortality rates. METHODS: Mortality rates/100,000 population for MS and all causes were calculated using data derived from Statistics Canada, age-standardized to the 2006 population. RESULTS: The average annual Canadian MS mortality rate, 1975-2009 was 1.23/100,000. Five-year rates for 1975-79, 1980-84, 1985-89, 1990-94, 1995-99, 2000-04, 2005-09 were: 1.16, 0.94, 1.01, 1.16, 1.30, 1.43, 1.33. Trend analysis showed mortality rates over the entire 35 years were stable (average annual percent change of less than one percent). The average annual 1975-2009 rates for females and males were 1.45 and 0.99. Five-year female rates were always higher than males. Regardless of gender, there was a decrease in MS mortality rates in the 0-39 age group and increases in the 60-69, 70-79, and 80+ groups over time. In contrast, there were decreases in all-cause mortality rates across each age group. The highest MS mortality rates for 1975-2009 were consistently in the 50-59 and 60-69 groups for both genders, while the highest all-cause mortality rates were in the 80+ group. CONCLUSIONS: Changes in the age distribution of MS mortality rates indicate a shift to later age at death, possibly due to improved health care. However MS patients remain disadvantaged relative to the general population and changes in age at death are not reflected in decreased mortality rates.

Parental concern about vaccine safety in Canadian children partially immunized at age 2: a multivariable model including system level factors.

Children who begin but do not fully complete the recommended series of childhood vaccines by 2 y of age are a much larger group than those who receive no vaccines. While parents who refuse all vaccines typically express concern about vaccine safety, it is critical to determine what influences parents of 'partially' immunized children. This case-control study examined whether parental concern about vaccine safety was responsible for partial immunization, and whether other personal or system-level factors played an important role. A random sample of parents of partially and completely immunized 2 y old children were selected from a Canadian regional immunization registry and completed a postal survey assessing various personal and system-level factors. Unadjusted odds ratios (OR) and adjusted ORs (aOR) were calculated with logistic regression. While vaccine safety concern was associated with partial immunization (OR 7.338, 95% CI 4.138-13.012), other variables were more strongly associated and reduced the strength of the relationship between concern and partial immunization in multivariable analysis (aOR 2.829, 95% CI 1.151-6.957). Other important factors included perceived disease susceptibility and severity (aOR 4.629, 95% CI 2.017-10.625), residential mobility (aOR 3.908, 95% CI 2.075-7.358), daycare use (aOR 0.310, 95% CI 0.144-0.671), number of needles administered at each visit (aOR 7.734, 95% CI 2.598-23.025) and access to a regular physician (aOR 0.219, 95% CI 0.057-0.846). While concern about vaccine safety may be addressed through educational strategies, this study suggests that additional program and policy-level strategies may positively impact immunization uptake.

The pot calling the kettle black: the extent and type of errors in a computerized immunization registry and by parent report.

BACKGROUND: Accurate classification of children's immunization status is essential for clinical care, administration and evaluation of immunization programs, and vaccine program research. Computerized immunization registries have been proposed as a valuable alternative to provider paper records or parent report, but there is a need to better understand the challenges associated with their use. This study assessed the accuracy of immunization status classification in an immunization registry as compared to parent report and determined the number and type of errors occurring in both sources. METHODS: This study was a sub-analysis of a larger study which compared the characteristics of children whose immunizations were up to date (UTD) at two years as compared to those not UTD. Children's immunization status was initially determined from a population-based immunization registry, and then compared to parent report of immunization status, as reported in a postal survey. Discrepancies between the two sources were adjudicated by review of immunization providers' hard-copy clinic records. Descriptive analyses included calculating proportions and confidence intervals for errors in classification and reporting of the type and frequency of errors. RESULTS: Among the 461 survey respondents, there were 60 discrepancies in immunization status. The majority of errors were due to parent report (n = 44), but the registry was not without fault (n = 16). Parents tended to erroneously report their child as UTD, whereas the registry was more likely to wrongly classify children as not UTD. Reasons for registry errors included failure to account for varicella disease history, variable number of doses required due to age at series initiation, and doses administered out of the region. CONCLUSIONS: These results confirm that parent report is often flawed, but also identify that registries are prone to misclassification of immunization status. Immunization program administrators and researchers need to institute measures to identify and reduce misclassification, in order for registries to play an effective role in the control of vaccine-preventable disease.

Illicit and prescription drug problems among urban Aboriginal adults in Canada: the role of traditional culture in protection and resilience.

Illicit and prescription drug use disorders are two to four times more prevalent among Aboriginal peoples in North America than the general population. Research suggests Aboriginal cultural participation may be protective against substance use problems in rural and remote Aboriginal communities. As Aboriginal peoples continue to urbanize rapidly around the globe, the role traditional Aboriginal beliefs and practices may play in reducing or even preventing substance use problems in cities is becoming increasingly relevant, and is the focus of the present study. Mainstream acculturation was also examined. Data were collected via in-person surveys with a community-based sample of Aboriginal adults living in a mid-sized city in western Canada (N = 381) in 2010. Associations were analysed using two sets of bootstrapped linear regression models adjusted for confounders with continuous illicit and prescription drug problem scores as outcomes. Psychological mechanisms that may explain why traditional culture is protective for Aboriginal peoples were examined using the cross-products of coefficients mediation method. The extent to which culture served as a resilience factor was examined via interaction testing. Results indicate Aboriginal enculturation was a protective factor associated with reduced 12-month illicit drug problems and 12-month prescription drug problems among Aboriginal adults in an urban setting. Increased self-esteem partially explained why cultural participation was protective. Cultural participation also promoted resilience by reducing the effects of high school incompletion on drug problems. In contrast, mainstream acculturation was not associated with illicit drug problems and served as a risk factor for prescription drug problems in this urban sample. Findings encourage the growth of programs and services that support Aboriginal peoples who strive to maintain their cultural traditions within cities, and further studies that examine how Aboriginal cultural practices and beliefs may promote and protect Aboriginal health in an urban environment.

Racial discrimination, post traumatic stress, and gambling problems among urban Aboriginal adults in Canada.

Little is known about risk factors for problem gambling (PG) within the rapidly growing urban Aboriginal population in North America. Racial discrimination may be an important risk factor for PG given documented associations between racism and other forms of addictive behaviour. This study examined associations between racial discrimination and problem gambling among urban Aboriginal adults, and the extent to which this link was mediated by post traumatic stress. Data were collected via in-person surveys with a community-based sample of Aboriginal adults living in a mid-sized city in western Canada (N = 381) in 2010. Results indicate more than 80 % of respondents experienced discrimination due to Aboriginal race in the past year, with the majority reporting high levels of racism in that time period. Past year racial discrimination was a risk factor for 12-month problem gambling, gambling to escape, and post traumatic stress disorder (PTSD) symptoms in bootstrapped regression models adjusted for confounders and other forms of social trauma. Elevated PTSD symptoms among those experiencing high levels of racism partially explained the association between racism and the use of gambling to escape in statistical models. These findings are the first to suggest racial discrimination may be an important social determinant of problem gambling for Aboriginal peoples. Gambling may be a coping response that some Aboriginal adults use to escape the negative emotions associated with racist experiences. Results support the development of policies to reduce racism directed at Aboriginal peoples in urban areas, and enhanced services to help Aboriginal peoples cope with racist events.

Racial discrimination experienced by aboriginal university students in Canada.

OBJECTIVES: Racial discrimination is an established life course social determinant of health associated with adverse psychological outcomes among minority populations. However, little is known about the extent to which Aboriginal people in Canada may experience racial discrimination and consequent adverse psychological effects. This study sought to measure the extent to which Aboriginal university students living in an urban area of Canada experienced racism, to triangulate this evidence with US data and qualitative findings, and to examine the impact of these experiences on mental health. METHODS: Data for this mixed method study were collected via in-person surveys with a volunteer sample of Aboriginal university students (n = 60) living in a mid-sized city in central Canada in 2008-2009. RESULTS: Results indicate Aboriginal university students experienced more frequent racism across a greater number of life situations than African- and Latino-American adults in the United States. Student reactions to these experiences were symptomatic of what has been termed racial battle fatigue in the United States. Students who considered themselves traditional or cultural Aboriginal persons were significantly more likely to experience discrimination. CONCLUSIONS: Results underline the need for policies aimed at reducing racism directed at Aboriginal people in urban areas and the growth of services to help Aboriginal people cope with these experiences. Results highlight the need for further research to determine the potential pathogenic consequences of racial discrimination for Aboriginal people in Canada.

Health-related quality of life and comorbidities associated with lumbar spinal stenosis.

BACKGROUND CONTEXT: Spinal stenosis is one of the most commonly diagnosed pathologies of the lumbar spine and the leading indication for spine surgery in adults aged 65 years and older. Yet, the burden of lumbar spinal stenosis (LSS) alone, and in combination with common comorbidities, on health-related quality of life (HRQL) is unknown as are comorbidities specifically associated with this chronic condition. PURPOSE: To estimate the illness burden of LSS on HRQL, adjusting for the effects of specific comorbidities, age, and gender, and investigate whether specific comorbidities are associated with the condition. STUDY DESIGN/SETTING: A community-based cohort of 245 patients diagnosed with LSS was assembled and compared with a representative sample of 7,489 adults from the base population of Albertans responding to the Canadian Community Health Survey on HRQL and comorbidities. METHODS: Health-related quality-of-life data were acquired through interviews for both groups using the Health Utilities Index Mark 3 (HUI3). Both groups were also queried about the presence of 13 specific chronic conditions. Linear regression was used to model HUI3 scores as a function of group, age, gender, and specific comorbid conditions. Logistic regression was used to compare the odds of having particular comorbid conditions between the LSS and general population groups. RESULTS: The mean unadjusted overall HUI3 scores were 0.60 for the LSS group and 0.85 for the general population (1=perfect health). After adjustment, HRQL deficits four times that deemed a clinically important difference remained between the groups. Controlling age and gender, the prevalence of arthritis, migraines, hypertension, and incontinence was significantly greater in the LSS group as compared with the general population sample. CONCLUSIONS: Diagnosed LSS is associated with a very substantial burden of illness that is compounded by associated comorbidities, with implications for clinical care, health-care policy decisions, and research. Attention to comorbidities is particularly important in LSS.

Enculturation and alcohol use problems among aboriginal university students.

OBJECTIVE: To examine associations between aboriginal enculturation, Canadian acculturation, and alcohol problems among aboriginal university students living in an urban area in Canada. METHODS: Data for this mixed methods study were collected through in-person surveys with a convenience sample of aboriginal university students (n = 60) in 2008/2009. RESULTS: Students evidenced high levels of aboriginal enculturation and Canadian acculturation. aboriginal enculturation was significantly associated with reduced alcohol problems for aboriginal university students. There was no association between Canadian acculturation and alcohol problems. Qualitative findings suggest aboriginal cultural practices helped students cope with problems in their daily lives and provided them with both personal and social rewards. CONCLUSIONS: This study found aboriginal enculturation was significantly associated with reduced alcohol problems among aboriginal university students. Results support the growth of programs and services that encourage aboriginal students to maintain their cultural identity within the university setting.

Using funnel plots in public health surveillance.

BACKGROUND: Public health surveillance is often concerned with the analysis of health outcomes over small areas. Funnel plots have been proposed as a useful tool for assessing and visualizing surveillance data, but their full utility has not been appreciated (for example, in the incorporation and interpretation of risk factors). METHODS: We investigate a way to simultaneously focus funnel plot analyses on direct policy implications while visually incorporating model fit and the effects of risk factors. Health survey data representing modifiable and nonmodifiable risk factors are used in an analysis of 2007 small area motor vehicle mortality rates in Alberta, Canada. RESULTS: Small area variations in motor vehicle mortality in Alberta were well explained by the suite of modifiable and nonmodifiable risk factors. Funnel plots of raw rates and of risk adjusted rates lead to different conclusions; the analysis process highlights opportunities for intervention as risk factors are incorporated into the model. Maps based on funnel plot methods identify areas worthy of further investigation. CONCLUSIONS: Funnel plots provide a useful tool to explore small area data and to routinely incorporate covariate relationships in surveillance analyses. The exploratory process has at each step a direct and useful policy-related result. Dealing thoughtfully with statistical overdispersion is a cornerstone to fully understanding funnel plots.

The role of family, religiosity, and behavior in adolescent gambling.

Predictors of adolescent gambling behavior were examined in a sample of 436 males and females (ages 13-16). A biopsychosocial model was used to identify key variables that differentiate between non-gambling and gambling adolescents. Logistic regression found that, as compared to adolescent male non-gamblers, adolescent male gamblers were older, had more conflict in their family, were more likely to have used drugs, and have peers that gamble. Compared to adolescent female non-gamblers, adolescent female gamblers had more attention and thought problems, and scored higher on rule-breaking. For both males and females, religiosity was a protective factor against involvement in gambling. Some of the results are consistent with previous research, while some of these findings are unique to this study. These results shed light on factors to consider when developing programs to combat the negative impacts of gambling on adolescents.

Prevalence and correlates of 12-month prescription drug misuse in Alberta.

OBJECTIVE: We examined the prevalence and correlates of prescription drug misuse (PDM) in a population-based sample of adults from Alberta. METHODS: Data were collected from 3511 adults in Alberta aged 18 years and older in 2002 using a computer-aided telephone survey; the survey response rate was 57.4%. RESULTS: The prevalence of 12-month PDM in Alberta was 8.2% in 2002. Opiates were the most frequently misused drug class, followed by sedatives, stimulants, and tranquilizers. Current disability was particularly associated with PDM. Odds of PDM were also elevated among adult students and adults with a high school diploma relative to adults with a post-secondary degree. Past-year problem gambling, illicit drug use, and alcohol use and dependence were each associated with PDM, while past-year binge drinking and daily smoking were not. CONCLUSIONS: Findings suggest PDM was an important public health concern in Alberta in 2002. Estimates suggest prescription use and misuse have increased substantially in Canada since that time. There is an urgent need for an ongoing assessment of this evolving problem so that effective prevention and therapeutic strategies can be developed.

An integrated framework for the geographic surveillance of chronic disease.

BACKGROUND: Geographic public health surveillance is concerned with describing and disseminating geographic information about disease and other measures of health to policy makers and the public. While methodological developments in the geographical analysis of disease are numerous, few have been integrated into a framework that also considers the effects of case ascertainment bias on the effectiveness of chronic disease surveillance. RESULTS: We present a framework for the geographic surveillance of chronic disease that integrates methodological developments in the spatial statistical analysis and case ascertainment. The framework uses an hierarchical approach to organize and model health information derived from an administrative health data system, and importantly, supports the detection and analysis of case ascertainment bias in geographic data. We test the framework on asthmatic data from Alberta, Canada. We observe high prevalence in south-western Alberta, particularly among Aboriginal females. We also observe that persons likely mistaken for asthmatics tend to be distributed in a pattern similar to asthmatics, suggesting that there may be an underlying social vulnerability to a variety of respiratory illnesses, or the presence of a diagnostic practice style effect. Finally, we note that clustering of asthmatics tends to occur at small geographic scales, while clustering of persons mistaken for asthmatics tends to occur at larger geographic scales. CONCLUSION: Routine and ongoing geographic surveillance of chronic diseases is critical to developing an understanding of underlying epidemiology, and is critical to informing policy makers and the public about the health of the population.

Prevalence of multiple sclerosis in First Nations people of Alberta.

BACKGROUND: Multiple Sclerosis (MS) is reported to be uncommon among North American aboriginals despite frequent intermarriage with people of European ancestry, but few population-based studies have been conducted. The purpose of this study was to determine the prevalence of MS among First Nations aboriginal people in Alberta, Canada compared to the general population. METHODS: All hospital in-patient and physician fee-for-service records between 1994 and 2002 where a diagnosis of MS was mentioned were extracted from government health databases in the province of Alberta. First Nations people can be identified since the federal government (Health Canada) pays health care insurance premiums on their behalf. Multiple Sclerosis prevalence per 100,000 population for both First Nations people and the general population of Alberta were calculated for each year during this time span. RESULTS: Among First Nations in Alberta, MS prevalence was 56.3 per 100,000 in 1994 and 99.9 per 100,000 in 2002, an increase of 43.6%. In 2002 prevalence was 158.1 and 38.0 for females and males respectively, a female to male ratio of 4.2:1. Multiple Sclerosis prevalence among the general population of Alberta was 262.6 per 100,000 in 1994 and 335.0 per 100,000 in 2002, an increase of 21.6%. In 2002 prevalence was 481.5 and 187.5 for females and males respectively, a female to male ratio of 2.6:1. Peak prevalence for both First Nations and general population females in 2002 was age 50-59, also 50-59 for both First Nations and general population males. CONCLUSION: While MS prevalence in First Nations people is lower than in the general population of Alberta, it is not rare by worldwide standards.

Incidence of multiple sclerosis among First Nations people in Alberta, Canada.

Multiple sclerosis (MS) is thought to be rare among North American aboriginals, although few population-based frequency studies have been conducted. Data from government health databases were used to describe the incidence of MS among First Nations aboriginal people in the province of Alberta compared to the general population from 1994 to 2002. The general population rates were consistently higher than First Nations rates, but were essentially stable across this time span for both groups. For First Nations the MS incidence was 7.6 per 100,000 and 20.6 per 100,000 for the general population in 2002. During 2000-2002 for First Nations the incidence was 12.7 for females and 7.6 for males, with a female-to-male ratio of 1.7:1. During the same period the general population incidence was 32.2 for females and 12.7 for males, with a female-to-male ratio of 2.5:1. The peak incidence for both First Nations and the general population of Alberta was in the age group 30-39 years in 2002. The high incidence rates are consistent with high prevalence rates reported for both groups in 2002: 99.9 per 100,000 for First Nations and 335.0 per 100,000 for the general population. While the MS incidence in First Nations people is lower than in the general population of Alberta, it is not rare by worldwide standards.

Modelling geographic variations in West Nile virus.

BACKGROUND: This paper applies a method for modelling the spatial variation of West Nile virus (WNv) in humans using bird, environmental and human testing data. METHODS: We used data collected from 503 Alberta municipalities. In order to manage the effects of residual spatial autocorrelation, we used generalized linear mixed models (GLMM) to model the incidence of infection. RESULTS: There were 275 confirmed cases of WNv in the 2003 calendar year in Alberta. Our spatial model indicates that living in the grasslands natural region and levels of human testing are significant positive predictors of WNv; living in an urban area is a significant negative predictor. CONCLUSION: Infected bird data contribute little to our model. The variability of West Nile virus incidence in Alberta may be partly confounded by the variations in the rate of testing in different parts of the province. However, variation in infection is also associated with known environmental risk factors. Our findings are consistent with existing knowledge of WNv in North America.

Direct health care costs after traumatic spinal cord injury.

BACKGROUND: The objective was to quantify direct health care costs attributable to traumatic spinal cord injury (SCI). METHODS: This population-based cohort study followed individuals with SCI from date of injury to 6 years postinjury. SCI cases were matched to a comparison group randomly selected from the general population. Administrative data from a Canadian province with a universal publicly funded health care system and centralized health databases were used. Costs included hospitalizations, physician services, home care, and long-term care. RESULTS: Attributable costs in the first year were $121,600 (2002 $CDN) per person with a complete SCI, and $42,100 per person with an incomplete injury. In the subsequent 5 years, annual costs were $5,400 and $2,800 for persons with complete and incomplete SCIs, respectively. CONCLUSION: Direct costs in the first year after SCI are substantial. In the subsequent 5 years, individuals with SCI will continue to accrue greater costs than the general public.

Depression following traumatic spinal cord injury.

OBJECTIVES: To describe the epidemiology of depression following traumatic spinal cord injury (SCI) and identify risk factors associated with depression. METHODS: This population-based cohort study followed individuals from date of SCI to 6 years after injury. Administrative data from a Canadian province with a universal publicly funded health care system and centralized databases were used. A Cox proportional hazards model was developed to identify risk factors. RESULTS: Of 201 patients with SCI, 58 (28.9%) were treated for depression. Individuals at highest risk were those with a pre-injury history of depression [hazard rate ratio (HRR) 1.6; 95% CI: 1.1-2.3], a history of substance abuse (HRR 1.6; 95% CI: 1.2-2.3) or permanent neurological deficit (HRR 1.6; 95% CI: 1.2-2.1). CONCLUSION: Depression occurs commonly and early in persons who sustain an SCI. Both patient and injury factors are associated with the development of depression. These should be used to target patients for mental health assessment and services during initial hospitalization and following discharge into the community.

Medical and psychiatric comorbidity and health care use among children 6 to 17 years old.

BACKGROUND: The association of psychiatric disorders (PDs) with other PDs and medical disorders (MDs) has been insufficiently explored in children and adolescents. OBJECTIVES: To estimate medical and psychiatric comorbidity present in children with PDs and to determine the medical service usage of children with PDs. DESIGN: We use administrative health care data to describe the health care provided for study children. Psychiatric disorders were classified into the following 3 categories: psychosis, emotion, and behavior. We used logistic regression to assess medical comorbidity for each category. Psychiatric comorbidity was determined using chi(2) test analysis. Health care use was determined by comparing the frequency of visits for MDs and PDs between children with PDs and children without PDs. SETTING: We studied 406,640 children (50.6% male) between 6 and 17 years old, living in Alberta, Canada, during the fiscal year April 1, 1995, through March 31, 1996. RESULTS: A PD was diagnosed in 32,214 (60.3% male) children. Psychiatric comorbidity was present in 13.6% of the children; comorbidity existed in all 3 psychiatric groups and peaked in postpubertal children. More girls than boys had significant medical comorbidity. Significant odds ratios (ORs) for girls varied from 1.2 (behavior and sinusitis, bronchitis, and chronic disorders; psychosis, and menstrual problems) to 15.3 (behavior and developmental delay). Among boys, the highest OR was seen with the combination of behavior and developmental delay (OR, 8.3) and psychosis and poisoning (OR, 8.2). With ORs ranging from 4.6 to 15.3, developmental delay consistently had high ORs for both sexes and all 3 types of PDs. Poisoning also had high ORs (3.3-14.1) with all 3 PDs and both sexes. Among girls, disorders associated with pregnancy and the genitourinary system had modest associations (OR, 1.9-2.2, for behavior) to moderate (OR, 2.5-4.0, for emotion). Children with PDs had significantly greater medical service usage than did children without PDs. Girls had greater medical health care usage than boys. Psychiatric service usage was similar for both sexes. CONCLUSIONS: Medical and psychiatric comorbidity exist in children with PDs. Girls are more commonly affected. Health care usage is higher in children with PDs.