1987 1994 2002 1997 1998 1996 1997 2007 1996 1999 1995 2002 1993 2002 1995 1998a 2005 2004 2002 2003 2004 2002 1993 1995 1999 1993 1995 In this article, a prevalence-based cost-of-illness analysis was performed in 8- to 18-year-old children and adolescents with anxiety disorders, who were referred to treatment. The primary aim of this study was to establish the societal costs of illness in families with a clinically anxious child, using the bottom-up approach by means of a prospective cost diary. A secondary aim of this study was to investigate the discriminative validity of the prospective cost diary by comparing the costs related to anxiety, psychological, physical and other problems in families with a clinically anxious child to the same costs in families from the general population. The third aim of this study was to establish convergent validity by comparing bottom-up acquired health care costs obtained with the cost diaries of the clinically anxious children with top-down acquired health care costs of children with a primary diagnosis of anxiety disorder. Materials and Methods Participants M n 1996 n n n n n n n n n n n n χ 2 p  F p F p M n n n 1997 n n All children and parents received and signed a written informed consent after receiving oral and written information on the study. Clinically anxious children, their siblings and parents were assessed before treatment and families from the general population were only measured once. Furthermore, all family members had to fill in a battery of questionnaires, including a prospective cost diary. Anxiety Disorders Interview Schedule 2001 2001 Prospective Cost Diary 1980 2000 Unit Prices 1982 2004 2005 2005 2004 2005 2004 Cost-of-illness The primary aim of this study was to calculate the societal burden of illness of families of clinically anxious youth in The Netherlands. The cost-of-illness study was performed from a societal perspective and included direct health care costs, direct non-health care costs, indirect costs and out-of-pocket costs. 2000 1997 1997 Discriminative Validity To determine the discriminative validity of the prospective cost diary, the societal costs of the 118 families of anxious children were compared to the societal costs of 41 families from the general population. For this purpose, all costs related to the child, irrespective of reason, were taken into account (i.e. psychological, physical or other). For both groups, the costs per family over a period of 2 weeks were extrapolated to a period of 1 year to obtain the annual costs per child for both groups. It was hypothesized that costs for anxiety problems were higher in the clinically anxious group compared to the general population but comparable between the two groups for psychological, physical and other problems. Convergent Validity To establish convergent validity, health care costs per child per year obtained with the prospective cost diaries of 118 clinically anxious children were compared with the health care costs of children with a primary diagnosis of anxiety disorder, according to top-down registrations. For this comparison, only health-care costs due to anxiety of the child were considered, because the costs obtained with the top-down registration applied to children with a primary diagnosis of anxiety disorder and only consisted of costs related to the health care sector. 2002 2002 1977 1977 2002 2005 Statistical Analysis 1997 2000 1998 Results Cost-of-illness 1 Z p n p p Table 1 n   Costs per unit Total resource use (2 weeks) Total costs (2 weeks) Total costs per child (2 weeks) Total costs per child a year     Sum Sum M M Direct health care costs Psychologist 1 0.00 0.00 0.00 0.00 Psychiatrist 1 0.00 0.00 0.00 0.00 G.P practice 1 3.00 60.60 0.51 (4.14) 13.35 (108) G.P. telephone 1 1.00 10.10 0.09 (0.93) 2.23 (57.98) Anxiety medication 2 14.25 10.26 0.09 (0.50) 2.26 (13.00) Pharmacists fee 1 14.25 91.91 0.78 (4.50) 20.28 (117) Institutionalized treatment 5 20.00 3,286 27.85 (213) 724 (5,537) Day treatment 5 30.00 2,876 24.37 (152) 634 (3,940)  Subtotal     6,335 53.69 (261) 1,396 (6,773)  Bootstrapped subtotal       52.78 (24.05) 1,371 (583) Direct non-health care costs Paid house keeper 1 2.00 25.44 0.22 (2.34) 5.61 (60.84) Informal care 1 32.00 269 2.28 (19.04) 59.23 (495)  Subtotal     294 2.50 (19.16) 64.84 (498)  Bootstrapped subtotal       2.43 (1.76) 68.15 (47.59) Indirect costs Paid work 1 83.29 2,888 24.48 (154) 636 (4003) Unpaid work 1 4.00 33.60 0.28 (3.09) 7.40 (80.34) Loss of leisure time 1 43.00 361 3.06 (16.47) 79.59 (428) Household work 1 6.50 54.60 0.46 (4.03) 12.03 (105) School absence 3 474 2,070 17.55 (57.89) 456.20 (1,505)  Subtotal     5,408 45.83 (198) 1,191.64 (5,135)  Bootstrapped subtotal       46.12 (18.22) 1,193.64 (473) Out-of-pocket costs Transportation 1 126 20.20 0.17 (1.41) 4.42 (36.66) Own contribution alternative treatment     350 2.97 (32.22) 77.12 (838) Own contribution medication not prescribed     63.30 0.54 (5.83) 13.95 (152)  Subtotal     434 3.67 (38.22) 95.52 (994)  Bootstrapped subtotal       3.86 (36.48) 97.52 (94.08) Total costs     12,471 106 (340) 2,748 (8,841) Bootstrapped total costs       104 (32.45) 2,749 (815) 1 2004 2 3 4 5 2005 Discriminative Validity 2 Table 2 n   Anxiety reason Psychological reason Physical reason Other reason Total a year   Cl. anx. Gen. Cl. anx. Gen. Cl. anx. Gen. Cl. anx. Gen. Cl. anx. Gen. Direct health care costs Psychologist/psychiatrist 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 G.P practice 13.35 0.00 4.45 0.00 13.35 0.00 0.00 0.00 28.86 0.00 G.P. telephone 2.23 0.00 2.23 0.00 4.45 0.00 0.00 0.00 8.84 0.00 Hospital visit 0.00 0.00 0.00 0.00 34.37 98.80 17.19 0.00 51.48 98.80 Emergence visit hospital 0.00 0.00 0.00 0.00 30.63 0.00 0.00 0.00 30.68 0.00 Medication 2.26 0.00 2.29 0.00 6.80 4.68 0.22 0.00 11.70 4.68 Pharmacist fee 20.25 0.00 18.48 0.00 29.84 20.54 1.42 0.00 69.94 20.54 Day treatment 634 0.00 0.00 0.00 0.00 0.00 0.00 0.00 634 0.00 Institutionalized treatment 724 0.00 0.00 0.00 0.00 0.00 0.00 0.00 724 0.00  Subtotal 1,396 0.00 27.44 0.00 119 124 18.83 0.00 1,559 124  Bootstrapped subtotal                 1,521 124 Direct non-health care costs House keeper 5.61 0.00 0.00 0.00 0.00 0.00 8.41 0.00 14.04 0.00 Informal care 59.23 0.00 0.00 0.00 0.00 0.00 14.81 0.00 74.10 0.00  Subtotal 64.83 0.00 0.00 0.00 0.00 0.00 23.21 0.00 88.05 0.00  Bootstrapped subtotal                 87.21 0.00 Indirect costs Paid work 636 0.00 0.00 0.00 0.00 0.00 7.67 0.00 644 0.00 Unpaid work 7.40 0.00 0.00 0.00 0.00 0.00 0.00 0.00 7.28 0.00 Leisure time loss 79.59 0.00 0.00 0.00 0.00 0.00 0.00 0.00 79.56 0.00 Household work 12.03 0.00 0.00 0.00 0.00 0.00 0.00 0.00 11.96 0.00 School absence 456 0.00 51.01 0.00 48.60 0.00 15.88 0.00 572 0.00  Subtotal 1,192 0.00 51.01 0.00 48.60 0.00 23.55 0.00 1,315 0.00  Bootstrapped subtotal                 1,305 0.00 Out-of-pocket costs Transportation 4.45 0.00 0.76 0.00 3.68 0.00 0.85 0.00 9.62 0.00 Alcohol 0.00 0.00 0.00 0.00 0.00 0.00 11.13 0.29 11.18 0.29 Caffeine 0.00 0.00 0.00 0.00 0.50 0.00 0.78 0.00 1.30 0.00 Tobacco 0.00 0.00 0.00 0.00 0.00 0.00 7.40 0.00 7.28 0.00 Own expenses 91.07 0.00 0.00 7.29 1.38 16.49 0.00 0.00 92.56 23.66  Subtotal 95.52 0.00 0.76 7.29 5.55 16.49 20.16 0.29 122 23.92  Bootstrapped subtotal                 125 23.89 Total costs 2,748 0.00 79.21 7.29 174 141 85.75 0.29 3,084 148 Bootstrapped total 2,790 0.00 78.44 7.23 173 142 86.99 0.32 3,070 147 Incremental costs (95% CI) −2,790 (−4,530 to −1,336) −71 (−205 to 0) −31 (−199 to 131) −87 (−152 to −33) −2,923 (−4,505 to −1,470) Costs of families from the general population were highest for physical reasons (95% of total costs). A small proportion of costs was assigned to psychological reasons (5% of total costs) and other reasons (0.2% of total costs). Despite the fact that five children in the control group met criteria for an anxiety disorder, families reported no costs for anxiety reasons. The total annual costs obtained from families of the general population amounted to a mean of €148 (SD = 523) per family. Z p 2 Convergent Validity 3 Table 3 Direct health care costs, anxiety based per child a year based on the Bottom-up and top-down approach   Bottom-up costs Top-down costs A day of hospitalization 0.00 203 Day treatment 0.00 1.84 Polyclinic visit 0.00 42.51 Categorical hospital 0.00 32.71 Remaining 0.00 7.60  Subtotal hospital care 0.00 287 General practitioner 15.58 58.27 Paramedical care 0.00 1.23   92.70 59.50 Pharmaceutical help 36.49 67.50 Mental health care 1,358 785 Management and care insurances 0.00 29.92 Total costs 1,410 1,229 3 Discussion To the authors’ knowledge, this is the first cost-of-illness study in clinically anxious children referred for treatment. The aim of this study was threefold. The first aim was to measure the societal costs of illness in clinically anxious children and their families, using a bottom-up approach by means of a prospective cost diary. The second aim was to investigate the discriminative validity of the prospective cost diary by comparing the costs of families with a clinically anxious child to the costs of families from the general population. The third aim of the study was to establish convergent validity by comparing bottom-up acquired health care costs of the clinically anxious children with top-down acquired health care costs of children with a primary diagnosis of anxiety. 1999 n 2006 2003 1997 1996 relative 1999 2006 2003 1999 2003 2002 2002 2005 An additional finding of this study concerns the difference in measuring costs in children with anxiety disorders compared to cost-of-illness studies in adults with anxiety disorders. The main difference of measuring costs in children with anxiety disorders, as other mental disorders in children, is that anxiety in the child does not only affect the child, but also the child’s family. Therefore, the costs concerning the child’s anxiety should also be measured at the family level. Although many would argue that the costs of illness for adults spill over to the family as well, studies on costs of anxiety disorders in adults usually do not include family members, especially not their children. So, in future research it may be interesting to assess the costs of adult anxiety disorders on a family level as well. For example, they might be more protective of their children and therefore increase their children’s health care consumption or more often let their child miss a day from school. Moreover, in adult cost-of-illness studies, productivity losses due to absence of paid work are measured. In children, these kind of productivity losses do not occur. However, alternatives such as costs due to absence from school should be taken into account, since school participation can be regarded as a productive activity, and (regular) absence from school may serve as a proxy for future productivity losses. With respect to the results regarding discriminative validity, total costs of families with clinically anxious children using a bottom-up approach were almost 21 times higher than costs of families from the general population. In line with the hypothesis, the difference in costs between families of clinically anxious children and families from the general population can largely be subscribed to the significant difference in anxiety-related costs, showing good discriminative validity of the cost diary on anxiety related costs. However, significant differences were also found on costs due to other reasons. In the prospective cost diary, the reasons for resource use were recorded based on subjective judgments by the parents. However, since anxiety is an internalizing disorder, parents may not always have been able to interpret children’s symptoms correctly. Therefore, they may have attributed costs mistakenly to non-anxiety reasons. For example, parents regularly reported a baby-sitter for a child old enough to stay on its own, if the child would not have been anxious. Another item that was reported as not being related to anxiety was extra travel expenses for the separation anxious child, who otherwise could have stayed at home. With respect to convergent validity, total direct health care costs related to anxiety were 13% lower using a top-down approach than using a bottom-up approach, which seems quite comparable. However, subdividing the costs into several cost categories showed that costs were distributed differently among the cost categories. For example, bottom-up acquired mental health care costs were 58% higher than top-down acquired mental health care costs. Furthermore, 23% of the total costs using a top-down approach were attributed to hospital care, whereas no hospital care costs were found using the bottom-up approach. Hence, convergent validity on total direct health care costs were quite comparable, while the specific cost categories differed between bottom-up and the top-down approach. These findings suggest that children, who are not yet referred for mental health care, might consume more medical hospital care compared to children who are referred for mental health care. Therefore, from a cost-of-illness perspective, it would also be interesting to investigate costs of families with children with anxiety disorders who are not referred for mental health treatment, using the cost dairy developed for this study. It might well be that these families have more medical health care costs, as the comparison with top-down acquired data suggests. 1997 1997 2007 2000 1998b 2002 1994 1996 1996