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Presents an obituary for Michael Joseph Chandler (1938-2019). Michael was trained as a developmental psychologist (though he preferred "genetic epistemologist") at Grinnell College (1960), the University of California, Berkeley (1966), the University of Geneva (1967), and The Menninger Foundation (1967-1968). He was subsequently hired at the University of Rochester (1968-1977) and was eventually appointed Professor, and later Professor Emeritus, at The University of British Columbia. Although always concerned with matters of social-cognitive development, his most recent program of research explored the role that culture plays in setting the course of identity development. Michael's program of research dealing with identity and epistemic development led to his twice being named a Distinguished Fellow of the Peter Wall Institute for Advanced Studies- work singled out for publication as a book and an invited Society for Research in Child Development Monograph titled Personal Persistence, Identity Development, and Suicide: A Study of Native and Non-Native North American Adolescents . His program of research was widely cited (often exceeding a thousand citations), and was featured in the World Health Organization's Global Report on the Social Determinants of Health. As a teacher and scholar, Michael was much loved by his students and colleagues and will be remembered fondly for his many contributions to the field and, more importantly, for relentlessly championing the success of others. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

[This corrects the article DOI: 10.1371/journal.pone.0191384.].

Background: Worldwide, Indigenous people have disproportionately higher rates of transport injuries. We examined disparities in injury-related hospitalizations resulting from transport incidents for three population groups in British Columbia (BC): total population, Aboriginal off-reserve, and Aboriginal on-reserve populations. We also examined sociodemographic, geographic and ethnic risk markers for disparities., Methods: We identified Aboriginal people through BC's universal health care insurance plan insurance premium group and birth and death record notations. We calculated crude incidence rate and Standardized Relative Risk (SRR) of hospitalization for unintentional transport injury, standardized for age, gender and Health Service Delivery Area (HSDA), relative to the total population of BC. We tested hypothesized associations of geographic, socio-economic, and employment-related characteristics of Aboriginal communities with SRR of transport injury by multivariable linear regression., Results: During the period 1991-2010, the SRR for the off-reserve Aboriginal population was 1.77 (95% CI: 1.71 to 1.83); and 2.00 (95% CI: 1.93 to 2.07) among those living on-reserve. Decline in crude rate and SRRs was observed over this period among both the Aboriginal and total populations of BC, but was proportionally greater among the Aboriginal population. The best-fitting multivariable risk marker model was an excellent fit (R2 = 0.912, p<0.001), predicted SRRs very close to observed values, and retained the following terms: urban residence, population per room, proportion of the population with a high school certificate, proportion of the population employed; and multiplicative interactions of Aboriginal ethnicity with population per room and proportion of the population employed., Conclusions: Disparities in risk of hospitalization due to unintentional transport injury have narrowed. Aboriginal ethnicity modifies the effects of socioeconomic risk factors. Continued improvement of socioeconomic conditions and implementation of culturally relevant injury prevention interventions are needed.

Background: Our objective was to explore intentional injury disparity between Indigenous populations and the total population in the province of British Columbia (BC), Canada. We focus on hospitalizations, including both self-inflicted injuries and injuries inflicted by others., Methods: We used data from BC's universal health care insurance plan, 1991 to 2010, linked to Vital Statistics databases. Indigenous people were identified through the insurance premium group, and birth and death records. Place of residence was identified through postal code. We calculated crude hospitalization incidence rates and the Standardized Relative Risk (SRR) of hospitalization, standardized by gender, 5-year age group, and Health Service Delivery Area (HSDA). With HSDA populations as the units of observation, linear regression was used to test hypothesized associations of Indigenous ethnicity, geographic, and socio-economic characteristics with SRR of injury., Results: During the period 1991-2010, the crude rate of hospitalization for intentional injuries was 8.4 per 10,000 person-years (95% confidence interval (CI): 8.3 to 8.5) for the total BC population, compared to 45.3 per 10,000 (95% CI: 44.5 to 46.1) for the Indigenous population. For both populations, risk declined over the period for injuries self-inflicted and inflicted by others. The linear regression model predicts that the off-reserve Indigenous population will have SRR of intentional injury 3.98 greater, and the on-reserve Indigenous population 4.17, greater than the total population. The final model was an excellent fit (R 2  = 0.912, F = 177.632, p < 0.001), and found that three variables - occupational risk, high school diploma, and university degree - each provide independent effects when interacting multiplicatively with Indigenous ethnicity., Conclusions: The observation of substantially declining rates of intentional injury for both the Indigenous and total BC populations is off-set by the high disparity in risk between the two populations, which will likely continue until Canada reduces disparity with respect to discriminatory practices, and physical, social, and economic conditions.

Background: Aboriginal people in British Columbia (BC), especially those residing on Indian reserves, have higher risk of unintentional fall injury than the general population. We test the hypothesis that the disparities are attributable to a combination of socioeconomic status, geographic place, and Aboriginal ethnicity., Methods: Within each of 16 Health Service Delivery Areas in BC, we identified three population groups: total population, Aboriginal off-reserve, and Aboriginal on-reserve. We calculated age and gender-standardized relative risks (SRR) of hospitalization due to unintentional fall injury (relative to the total population of BC), during time periods 1999-2003 and 2004-2008, and we obtained custom data from the 2001 and 2006 censuses (long form), describing income, education, employment, housing, proportions of urban and rural dwellers, and prevalence of Aboriginal ethnicity. We studied association of census characteristics with SRR of fall injury, by multivariable linear regression., Results: The best-fitting model was an excellent fit (R 2  = 0.854, p < 0.001) and predicted SRRs very close to observed values for the total, Aboriginal off-reserve, and Aboriginal on-reserve populations of BC. After stepwise regression, the following terms remained: population per room, urban residence, labor force participation, income per capita, and multiplicative interactions of Aboriginal ethnicity with population per room and labor force participation., Conclusions: The disparities are predictable by the hypothesized risk markers. Aboriginal ethnicity is not an independent risk marker: it modifies the effects of socioeconomic factors. Closing the gap in fall injury risk between the general and Aboriginal populations is likely achievable by closing the gaps in socioeconomic conditions.

Purpose: Measure population health impact, and socioeconomic, geographic, and ethnic predictors of iatrogenic injury., Methods: Within three groups (total population, Aboriginal off-reserve, and Aboriginal on-reserve) in each of 16 Health Service Delivery Areas (HSDAs) of British Columbia, Canada we calculated crude incidence and Standardized Relative Risk (SRR) of hospitalization for iatrogenic injury. We tested hypothesized associations between HSDA census characteristics and SRR, by multivariable regression., Results: Among hospitalizations due to any injury, 22.2% were iatrogenic. Crude rate of iatrogenic injury hospitalization was 20.4 per 10,000 person-years. Aboriginal rate was 24.4 per 10,000 and SRR was 1.57 (1.76 among females, 1.38 among males). Non-metropolitan HSDAs had higher SRRs. The best-fitting regression model was an excellent fit (R=0.836, p&lt;.001) and included education, income, house needs major repairs, population per room, and Aboriginal ethnicity., Conclusions: Iatrogenic injury has significant population health impact. Aboriginal people, especially females, have higher risk. Ethnicity and socioeconomic factors explain regional disparities.

Background: Disparities in injury rates between Aboriginal and non-Aboriginal populations in British Columbia (BC) are well established. Information regarding the influence of residence on disparities is scarce. We sought to fill these gaps by examining hospitalization rates for all injuries, unintentional injuries and intentional injuries across 24 years among i) Aboriginal and total populations; ii) populations living in metropolitan and non-metropolitan areas; and iii) Aboriginal populations living on- and off-reserve., Methods: We used data spanning 1986 through 2010 from BC's universal health care insurance plan, linked to vital statistics databases. Aboriginal people were identified by insurance premium group and birth and death record notations, and their residence was determined by postal code. "On-reserve" residence was established by postal code areas associated with an Indian reserve or settlement. Health Service Delivery Areas (HSDAs) were classified as "metropolitan" if they contained a population of at least 100,000 with a density of 400 or more people per square kilometre. We calculated the crude hospitalization incidence rate and the Standardized Relative Risk (SRR) of hospitalization due to injury standardizing by gender, 5-year age group, and HSDA. We assessed cumulative change in SRR over time as the relative change between the first and last years of the observation period., Results: Aboriginal metropolitan populations living off-reserve had the lowest SRR of injury (2.0), but this was 2.3 times greater than the general British Columbia metropolitan population (0.86). For intentional injuries, Aboriginal populations living on-reserve in non-metropolitan areas were at 5.9 times greater risk than the total BC population. In general, the largest injury disparities were evident for Aboriginal non-metropolitan populations living on-reserve (SRR 3.0); 2.5 times greater than the general BC non-metropolitan population (1.2). Time trends indicated decreasing disparities, with Aboriginal non-metropolitan populations experiencing the largest declines in injury rates., Conclusions: Metropolitan/non-metropolitan residence appears to be a more important predictor than on/off-reserve residence for all injuries and unintentional injuries, and the relationship was even more pronounced for intentional injuries. The persistent disparities highlight the need for culturally sensitive and geographically relevant injury prevention approaches.

Background: The current study examines what factors contribute to higher injury risk among Aboriginal peoples, compared to the total British Columbia (BC) population. We explore socioeconomic, geographic, and cultural factors, and combinations of these factors, that contribute to increased injury risk for Aboriginal peoples. This follows from our previously reported findings of improvements in injury risk over time for both the total and Aboriginal populations., Data and Methods: We use provincial population-based linked health care databases of hospital discharge records. We identify three population groups: total BC population, and Aboriginal populations living off-reserve, or on-reserve. For each group we calculate age and gender-standardized relative risks (SRR) of injury-related hospitalization, relative to the total population of BC, for two 5-year time periods (1999-2003, and 2004-2008). We use custom data from the 2001 and 2006 long-form Censuses that described income, education, employment, housing conditions, proportion of urban dwellers, proportion of rural dwellers, and prevalence of Aboriginal ethnicity. We use multivariable linear regression to examine the associations between the census characteristics and SRR of injury., Results: The best-fitting model was an excellent fit (R(2) = 0.905, p < 0.001) among the three population groups within Health Service Delivery Areas of BC. We find indicators in all three categories (socioeconomic, geographic, and cultural) are associated with disparity in injury risk. While the socioeconomic indicators (income, education, housing, employment) were shown to be highly correlated, only living in housing that needs major repair and occupational hazardousness, along with rural residence and Aboriginal ethnicity, remained in the final model. Our data show that cultural density is not associated with injury risk for Aboriginal peoples, and that living off-reserve is associated with reduced injury by improving socioeconomic and geographic conditions (compared to living on-reserve). Finally, our analyses show that Aboriginal status itself is associated with injury risk., Conclusions: Our findings confirm previous research indicating that geographical differences differentiate injury risk, including for Aboriginal populations, and that socioeconomic determinants are associated with health risks. Our analyses showing that Aboriginal status itself contributes to injury risk is new, but we can only speculate about pathway, and whether the causes are direct or indirect.

Background: Children and youth worldwide are at high risk of injury resulting in morbidity, disability or mortality. Disparities in risk exist between and within countries, and by sex and ethnicity. Our aim is to contribute data on disparities of injury rates for Aboriginal children and youth compared with those of the general population in British Columbia (BC), Canada, by examining risks for the two populations, utilizing provincial administrative data over a 24-year period., Methods: Hospital discharge records from the provincial health care database for children and youth were used to identify injury for the years 1986 to 2009. Within the total BC population, the Aboriginal population was identified. Crude rates and standardized relative risks (SRR) of hospitalization were calculated, by year and category of injury type and external cause, and compared to the total BC population for males and females under age 25 years., Results: Over the 24-year period, substantive decreases were found in hospitalization injury risks for children and youth in both Aboriginal and total populations, for both sexes, and for most categories and types of injuries. Risk in overall injury dropped by 69% for the Aboriginal population and by 66% for the total BC population, yet in every year, the Aboriginal population had a higher risk than the total BC population. There were over 70% declines in risks among females of intentionally inflicted injury by another, among both the Aboriginal and total BC populations. Risk of injury caused by transport vehicles has decreased by an overwhelming 83% and 72% for the Aboriginal male population and for the total BC male population, respectively., Conclusions: The over 70% declines in risks for females of intentionally inflicted injury by another, among both the Aboriginal and total BC populations is excellent news. Risk of injury caused by transport vehicles for males decreased overwhelmingly for both populations. Disparities in rates between the Aboriginal population and total BC population remain because of similarity in the proportional reductions among the two populations. Since the Aboriginal population started at a much higher risk, in absolute terms, the gap between the two populations is shrinking.

Background: Aboriginal people in British Columbia (BC) have higher injury incidence than the general population. This report describes variability in visits to primary care due to injury, among injury categories, time periods, geographies, and demographic groups., Methods: We used BC's universal health care insurance plan as a population registry, linked to practitioner payment and vital statistics databases. We identified Aboriginal people by insurance premium group and birth and death record notations. Within that population we identified those residing off-reserve according to postal code. We calculated crude incidence and Standardized Relative Risk (SRR) of primary care visit due to injury, standardized for age, gender and Health Service Delivery Area (HSDA), relative to the total population of BC., Results: During 1991 through 2010, the crude rate of primary care visit due to injury in BC was 3172 per 10,000 person-years. The Aboriginal off-reserve rate was 4291 per 10,000 and SRR was 1.41 (95 % confidence interval: 1.41 to 1.42). Northern and non-metropolitan HSDAs had higher SRRs, within both total BC and Aboriginal off-reserve populations. In every age and gender category, the HSDA-standardized SRR was higher among the Aboriginal off-reserve than among the total population. For all injuries combined, and for the categories of trauma, poisoning, and burn, between 1991 and 2010, crude rates and SRRs declined substantially, but proportionally more rapidly among the Aboriginal off-reserve population, so the gap between the Aboriginal off-reserve and total populations is narrowing, particularly among metropolitan residents., Conclusions: These findings corroborate our previous reports regarding hospitalizations due to injury, suggesting that our observations reflect real disparities and changes in the underlying incidence of injury, and are not merely artefacts related to health care utilization.

Population-level statistics indicating disparities in injury rates between Aboriginal and non-Aboriginal populations disguise considerable community-level heterogeneity. Using an ecological approach, we analyzed linked data from British Columbia's (BC) universal health care insurance plan, worker compensation, vital statistics, and census databases to identify community-level risk markers for hospitalization due to injury among the Aboriginal population of BC, Canada. Community standardized relative risks (SRR) of injury hospitalization relative to the total population of BC ranged from 0.24 to 9.35. Variables associated with increased SRRs included the following: higher proportions of crowded housing, housing in poor condition, participating in industries with greater risk of a work injury claim, being more remote, and at higher latitude. Higher income and more high school graduates were protective. In the best-fitting multivariable model, variables independently associated with SRR were proportion of the population with a high school certificate (RR = 0.89 per unit standard deviation change, 95 % confidence interval 0.83 to 0.94), and remoteness index (RR = 1.06, 95 % confidence interval (CI) 1.01 to 1.11). Results confirm profound diversity in Aboriginal communities across BC. SRRs of injury hospitalization increased as proportion of high school graduates dropped and remoteness increased. Promoting the educational attainment of community members should be an important focus of initiatives to improve health.

Background: Aboriginal people in British Columbia (BC) have higher injury incidence than the general population. Our project describes variability among injury categories, time periods, and geographic, demographic and socio-economic groups. This report focuses on unintentional falls., Methods: We used BC's universal health care insurance plan as a population registry, linked to hospital separation and vital statistics databases. We identified Aboriginal people by insurance premium group and birth and death record notations. We identified residents of specific Aboriginal communities by postal code. We calculated crude incidence and Standardized Relative Risk (SRR) of hospitalization for unintentional fall injury, standardized for age, gender and Health Service Delivery Area (HSDA), relative to the total population of BC. We tested hypothesized associations of geographic, socio-economic, and employment-related characteristics with community SRR of injury by linear regression., Results: During 1991 through 2010, the crude rate of hospitalization for unintentional fall injury in BC was 33.6 per 10,000 person-years. The Aboriginal rate was 49.9 per 10,000 and SRR was 1.89 (95% confidence interval 1.85-1.94). Among those living on reserves SRR was 2.00 (95% CI 1.93-2.07). Northern and non-urban HSDAs had higher SRRs, within both total and Aboriginal populations. In every age and gender category, the HSDA-standardized SRR was higher among the Aboriginal than among the total population. Between 1991 and 2010, crude rates and SRRs declined substantially, but proportionally more among the Aboriginal population, so the gap between the Aboriginal and total population is narrowing, particularly among females and older adults. These community characteristics were associated with higher risk: lower income, lower educational level, worse housing conditions, and more hazardous types of employment., Conclusions: Over the years, as socio-economic conditions improve, risk of hospitalization due to unintentional fall injury has declined among the Aboriginal population. Women and older adults have benefited more.

Background: Evidence from various jurisdictions has shown higher rates of injury for Aboriginal compared with non-Aboriginal populations. This study provides an overview of trends in hospitalization injury rates between the Aboriginal and total populations of one Canadian province, British Columbia., Data and Methods: Hospital discharge records from 1986 through 2010 were obtained from linked health care databases maintained by Population Data BC. Crude rates and standardized relative risks of hospitalization due to injury among Aboriginal people, relative to the total population of British Columbia, were calculated. Changes over time among males and females were compared for various types and causes of injury., Results: Throughout more than two decades, standardized risks of hospitalization for injury decreased among the Aboriginal and total populations of British Columbia. Larger decreases among the Aboriginal population than among the total population suggest that the gaps are closing. Downward trends in rates were found for most injury categories, and for males and females., Interpretation: The findings indicate narrowing of the gap in injury rates between the total population of British Columbia and the province's Aboriginal population.

Background: Aboriginal people in British Columbia (BC) have higher injury incidence than the general population, but information is scarce regarding variability among injury categories, time periods, and geographic, demographic and socio-economic groups. Our project helps fill these gaps. This report focuses on workplace injuries., Methods: We used BC's universal health care insurance plan as a population registry, linked to worker compensation and vital statistics databases. We identified Aboriginal people by insurance premium group and birth and death record notations. We identified residents of specific Aboriginal communities by postal code. We calculated crude incidence rate and Standardized Relative Risk (SRR) of worker compensation injury, adjusted for age, gender and Health Service Delivery Area (HSDA), relative to the total population of BC. We assessed annual trend by regressing SRR as a linear function of year. We tested hypothesized associations of geographic, socio-economic, and employment-related characteristics of Aboriginal communities with community SRR of injury by multivariable linear regression., Results: During the period 1987-2010, the crude rate of worker compensation injury in BC was 146.6 per 10,000 person-years (95% confidence interval: 146.4 to 146.9 per 10,000). The Aboriginal rate was 115.6 per 10,000 (95% CI: 114.4 to 116.8 per 10,000) and SRR was 0.88 (95% CI: 0.87 to 0.89). Among those living on reserves SRR was 0.79 (95% CI: 0.78 to 0.80). HSDA SRRs were highly variable, within both total and Aboriginal populations. Aboriginal males under 35 and females under 40 years of age had lower SRRs, but older Aboriginal females had higher SRRs. SRRs are declining, but more slowly for the Aboriginal population. The Aboriginal population was initially at lower risk than the total population, but parity was reached in 2006. These community characteristics independently predicted injury risk: crowded housing, proportion of population who identified as Aboriginal, and interactions between employment rate and income, occupational risk, proportion of university-educated persons, and year., Conclusions: As employment rates rise, so has risk of workplace injury among the Aboriginal population. We need culturally sensitive prevention programs, targeting regions and industries where Aboriginal workers are concentrated and demographic groups that are at higher risk.

Background: The project, Injury in British Columbia's Aboriginal Communities: Building Capacity while Developing Knowledge, funded by the Canadian Institutes of Health Research (CIHR), aims to expand knowledge on injury rates among First Nations communities in British Columbia (BC), Canada., Objective: The purpose is to improve understanding of community differences and to identify community-level risk and protective factors. Generally, injury incidence rates in the Aboriginal population in Canada greatly exceed those found in the non-Aboriginal population; however, variability exists between Aboriginal communities, which have important implications for prevention., Design: This study uses administrative records of deaths, hospitalizations, ambulatory care episodes, and workers' compensation claims due to injuries to identify communities that have been especially successful in maintaining low rates of injury., Results: The analysis of risk and protective factors extends the work of Chandler and Lalonde who observed that community efforts to preserve and promote Aboriginal culture and to maintain local control over community life are strongly associated with lower suicide rates., Conclusion: The discussion on psychological and cultural considerations on healing and reducing the rates of injury expands the work of McCormick on substance use in Aboriginal communities.

Our understanding of children's social competence has increased tremendously over the past two decades. There is increasing evidence to suggest that social-cognitive impairments are not restricted to children on the autistic spectrum, but rather may be associated with a host of developmental and acquired neurological conditions including learning disabilities, attention deficit disorder, traumatic brain injury, and stroke. Although many investigators have begun to bridge the gap between clinical practice and research by applying experimental tasks to clinical populations, few tools are available for the clinical evaluation of social competence, particularly in children. This study marks a series of first steps in the development of measures suitable for the assessment of children between 6 and 12 years of age. The results of the study provide data for a number of experimental tasks that have been adapted with clinical practice in mind. A discussion of the developmental progressions and the relationships among the measures is also included.

The development of cognitive control and its relation to overcoming Stroop interference was assessed in a sample (N= 65) of elementary-school children. Subjects alternately performed Stroop color-naming trials and word-reading trials. In separate blocks, the colored Stroop items were non-color words (incongruent condition) or rows of asterisks (neutral condition). Younger children showed both larger Stroop interference in error rates and a greater slowing of word reading in the incongruent condition compared with older children. We conducted analyses of response time distributions that assessed the degree of word-reading suppression applied by younger and older children. Surprisingly, these analyses indicated that younger children engaged in stronger suppression than older children. We propose that greater Stroop interference among younger children is not due to lack of ability to suppress word reading, but instead is the result of a failure to consistently maintain the task set of color naming.

Objective: To examine persistence with methylphenidate (MPH) therapy among children and youth in the general population., Method: We conducted a retrospective analysis of longitudinally organized, individual-specific anonymous data from linked prescription and health databases covering the population of British Columbia for 1990 through 1996. No prescriptions being filled for 4 months indicated cessation of one bout of therapy., Results: Among 16,945 identified MPH patients aged 19 years or under, overall duration of therapy was 584 days, and the average number of prescriptions received was 6.6. One-third of patients received 2 or fewer prescriptions, while 18% followed a chronic, continuous course. Among patients receiving more than 2 prescriptions, 50% of discrete therapy bouts lasted 4 months or less, and one-third of cases had multiple bouts of therapy (range 2 to 6 bouts). Younger age (that is, children aged 0 to 8 years, vs those aged 10 to 19 years), male sex, and receipt of initial prescription from a psychiatrist were associated with greater persistence., Conclusions: Enormous variability in persistence with MPH therapy and often-occurring low rates of persistence raises questions about the diligence with which MPH patients are selected, prepared, and followed in the general population. Special attention to the needs of older children and to the needs of girls is required, and discontinuities during children's therapy courses require explication.

The cross-cultural program of research presented here is about matters of temporal persistence--personal persistence and cultural persistence--and about solution strategies for solving the paradox of "sameness-in-change." The crux of this paradox resides in the fact that, on threat of otherwise ceasing to be recognizable as a self, all of us must satisfy at least two constitutive conditions. The first of these is that selves are obliged to keep moving or die, and, so, must continually change. The second is that selves must also somehow remain the same, lest all notions of moral responsibility and any commitment to an as yet unrealized future become nonsensical. Although long understood as a problem demanding the attention of philosophers, we argue that this same paradox arises in the ordinary course of identity development and dictates the different developmental routes taken by culturally mainstream and Aboriginal youth in coming to the identity-preserving conclusion that they and others are somehow continuous through time. Findings from a set of five studies are presented. The first and second studies document the development and refinement of a method for parsing and coding what young people say on the topic of personal persistence or self-continuity. Both studies demonstrate that it is not only possible to seriously engage children as young as age 9 or 10 years in detailed and codable discussions about personal persistence, but that their reasoning concerning such matters typically proceeds in an orderly and increasingly sophisticated manner over the course of their early identity development. Our third study underscores the high personal costs of failing to sustain a workable sense of personal persistence by showing that failures to warrant self-continuity are strongly associated with increased suicide risk in adolescence. Study four documents this same relation between continuity and suicide, this time at the macrolevel of whole cultures, and shows that efforts by Aboriginal groups to preserve and promote their culture are associated with dramatic reductions in rates of youth suicide. In the final study we show that different default strategies for resolving the paradox of personal persistence and change--Narrative and Essentialist strategies--distinctly characterize Aboriginal and non-Aboriginal youth.

Background: There are concerns about the frequency and appropriateness of psychostimulant drug prescription to children. In order to identify unusual or unexpected patterns of use or prescribing, we reviewed prescription of methylphenidate (Ritalin) to children and adolescents aged 19 years or less in British Columbia between 1990 and 1996., Methods: We obtained information about patients, physicians and prescriptions from British Columbia's Triplicate Prescription Program database for controlled drugs. Prescription data were available for the period Jan. 1, 1990, to Dec. 31, 1996. Linkage with the BC Linked Health Dataset provided additional demographic and health information., Results: In 1990, 1715 children received at least 1 prescription for methylphenidate (1.9 per 1000 children). By 1996, the number had increased to 10,881 children (11.0 per 1000). Because some children were prescribed methylphenidate in more than 1 year, we also calculated the frequency with which the drug was prescribed to children who had never received it before. This rate increased from 1.0 per 1000 children in 1990 to 4.7 per 1000 in 1995; the rate fell in 1996 to 3.5 per 1000. The number of children receiving methylphenidate varied across health regions of the province, from 12.0 to 35.4 per 1000. Use also varied by socioeconomic status quintile: in the 2 lowest (least privileged) quintiles, 21.6 per 1000 children received methylphenidate, compared with 18.4 per 1000 in the 3 highest quintiles (relative risk 1.2, 95% confidence interval 1.1-1.2). Pediatricians and psychiatrists wrote 23% and 21% of all prescriptions respectively. General practitioners accounted for 56% of all prescriptions and 41% of initial methylphenidate prescriptions. A claim for prior specialist consultation was found in 30% of such cases. Many of the children who received more than 10 prescriptions had seen 4 or more physicians. The average daily dosage prescribed differed little among general practitioners, pediatricians and psychiatrists, unlike the mean interval between successive prescriptions: 89.9 (standard deviation [SD] 68.2), 99.8 (SD 64.1) and 75.9 (SD 70.2) days respectively. Persistence with therapy was more likely when a psychiatrist provided the initial prescription, or with involvement of more than one specialty., Interpretation: Many trends and practices in the prescription of methylphenidate to children in British Columbia are consistent with other settings and accepted standards. Some aspects warrant closer investigation, including regional and socio-economic discrepancies in the distribution of patients, the relative involvement of primary and specialist care providers, continuity of care issues and time intervals between prescriptions.