Eur J Pediatr (2011) 170:65–73 causal indicators; p values were produced by means of the Wald test. A p value less than 0.05 was considered significant. As this is an exploratory study, no correction for multiple testing was envisaged. Results Cases versus controls We first looked at differences in health perception (Table 2). Statistical significant differences were seen for among others emotional problems, mobility, societal life, burden on family and for all burden sum scores. To illustrate this further, for instance for the F (family) item, 24.8% trauma cases scored a ‘moderate’ to ‘very severe’ problem, while only 6.8% in the control group. In line with these results, children in the trauma group had significant more health visits in the last month. The estimated relative risk R′ for “visiting more than once in the last month” was 1.7 (exact 95% CI = [1.1, 2.8]) for physician visits, 13 (exact 95% CI = [3.3, 113]) for physiotherapist visits and 3.5 (exact 95% CI = [1.1, 14.6]) for psychologist visits. Table 3 Observer variability 69 Reproducility Using the Bhapkar test, we found no statistically significant difference in the between-parents comparison, except for sensational problems and self-care in the trauma cases (in four out of 28 trauma cases scores differed; Table 3). Differences between parent and child were far more pronounced. In the trauma group, these differences reached statistical significance for among others pain, task and demands. In each of these items differences were caused by a higher severity score given by the parent, e.g. for pain eight (out of 29) parents scored moderate to severe problems whereas the child scored only mild. On the contrary, for the control cases significant differences were caused by higher scores for the child, e.g. for emotional 26 children scored moderate to severe problems and the parent only mild. Overall, differences were observed most often around the mild to moderate cut-off. Characteristics of the IROS items and covariate effects We first estimated how well the ‘effect indicators’ on their own would capture a unique construct, i.e. the underlying Parent–parent trauma cases Parent–parent controls Parent–child Trauma cases Parent–child controls P values for significant disagreement between raters by means of the Bhapkar test (* if <0.05). For some items, p values are not available (NA) because the same reply was given by all respondents Item B1a: emotional B1b: other mental B2a: pain B2b: other sensations B3: speech and voice B4: cardiorespiratory B5: intestinal, metabolic and horm. B6: urogenital and reproduction B7: locomotor system B8: skin D1: learning D2: tasks and demands D3: communication D4: mobility D5: self-care D6: domestic life D7: social relations D9: societal life S: structural F: family PB: physical burden MB: mental burden SB: social burden TB: total burden 0.067 0.309 0.165 0.031* 0.142 0.561 >0.999 0.309 0.067 0.309 0.309 0.309 0.067 0.031* 0.561 0.142 0.561 0.142 0.466 0.195 0.185 0.073 0.294 0.118 0.118 0.294 0.294 0.294 0.118 0.294 0.294 0.142 0.561 0.142 0.560 0.294 0.295 0.143 0.246 <0.001* 0.738 0.309 0.409 0.654 >0.999 0.031* 0.021* 0.067 0.409 0.309 0.309 0.561 0.044* 0.654 0.051 0.377 0.16 0.108 <0.001* 0.763 0.04 0.248 0.015* 0.017* 0.314 0.013* 0.739 0.739 0.412 0.563 0.078 0.563 0.09 0.175 0.592 0.0279* 0.068 0.003* 0.771 0.229