Clinical practice guidelines for monitoring children's behavioural development at the 18-month well-baby visit: A decision analysis comparing the expected benefit of two alternative strategies.

RATIONALE, AIMS AND OBJECTIVES: The current American Academy of Pediatrics policy calls for universal developmental screening (UDS) at the 18-month well-baby visit (18MWBV). In contrast, different clinical practice guidelines exist in other developed countries where only toddlers of concerned parents are referred for (selective) developmental screening (SDS). This study compares the expected benefit (EB) of these two strategies for monitoring children's behavioural development at the 18MWBV. METHOD: A clinical decision analysis was performed, with EB defined as gain (probability of screening when appropriate + probability of not screening when appropriate) minus cost (probability of screening when not appropriate + probability of not screening when not appropriate). Accordingly, a strategy's EB referred to its efficiency at distinguishing between toddlers who need to be referred for screening and those who do not. RESULTS: The EB of the UDS strategy was estimated at -0.242. In contrast, the EB of the SDS strategy was much greater at 0.326. In fact, the EB of the UDS strategy could only equal or surpass that of the SDS strategy if screening toddlers with a problem was considered almost five times more important than not screening well toddlers. However, our monitoring effort should be more evenly distributed between these two imperatives. Also, the evidence in favour of the SDS strategy remained largely unchanged after considering a broad range of values for the (unique) probabilities in the decision tree. CONCLUSION: There are many steps involved in the monitoring of children's early behavioural development, but when it comes to decide whether or not to use behavioural screening, there is evidence for adopting the SDS strategy, and screening only if a behavioural concern is being raised by parents.

The development of opposition-defiance during toddlerhood: a population-based cohort study.

OBJECTIVE: There is now emerging epidemiological evidence that a substantial proportion of toddlers in the general population may be experiencing a significant opposition-defiance problem before 2 years of age. This article describes the continuity and discontinuity in boys' and girls' opposition-defiance statuses during toddlerhood. METHOD: Data came from The Québec Longitudinal Study of Child Development, a survey of a representative birth cohort of children from the Canadian province of Québec. A time-specific latent variables (Markov) model was used to estimate the proportion of toddlers who cease or start to exhibit oppositional-defiant behaviors (ODBs) on a frequent basis between 17 and 29 months of age and to test for gender differences therein. RESULTS: A majority of toddlers who had exhibited ODBs on a frequent basis at 17 months of age were still doing so 1 year later. Also, a majority of toddlers who did exhibit ODBs on a frequent basis at 29 months of age had done so 1 year earlier. The results also show that there are more toddlers who start than stop exhibiting ODBs on a frequent basis during this period. Further, the continuity and discontinuity in toddlers' opposition-defiance statuses during this period did not vary between boys and girls, suggesting that gender differences in opposition-defiance have not yet emerged by the second half of the third year of life. CONCLUSION: The predictive accuracy of early opposition-defiance is very good, with a substantial proportion of toddlers experiencing a significant opposition-defiance problem throughout toddlerhood.

Gender differences in physical aggression: A prospective population-based survey of children before and after 2 years of age.

There has been much controversy over the past decades on the origins of gender differences in children's aggressive behavior. A widely held view is that gender differences emerge sometime after 2 years of age and increase in magnitude thereafter because of gender-differentiated socialization practices. The objective of this study was to test for (a) gender differences in the prevalence of physical aggression in the general population of 17-month-old children and (b) change in the magnitude of these differences between 17 and 29 months of age. Contrary to the differential socialization hypothesis, the results showed substantial gender differences in the prevalence of physical aggression at 17 months of age, with 5% of boys but only 1% of girls manifesting physically aggressive behaviors on a frequent basis. The results suggest that there is no change in the magnitude of these differences between 17 and 29 months of age.