Objective. Primarily, to determine the direct medical costs and productivity losses associated with complicated chickenpox (hospitalized cases) and, secondarily, to quantify the overall economic burden of chickenpox in Canada.
Methods. Direct medical resource consumption patterns were determined by chart review of 160 otherwise healthy children and 40 children with leukemia hospitalized for chickenpox. Children were selected from the database of the Immunization Monitoring Program Active (IMPACT), a network of 11 tertiary-care hospitals in Canada that collected information at the time of hospitalization from January 1991 to March 1996. An additional 26 healthy children hospitalized were recruited prospectively by IMPACT. Productivity losses (time lost from work and daily activities) were assessed by caregiver interviews. Treatment costs were determined from the patient, Ministry of Health, and societal perspectives.
Results. The average societal per case cost for complicated chickenpox in healthy children was $7060 and $8398, respectively, from the retrospective and prospective assessments. For children with leukemia, the direct medical cost was estimated at $7228. These costs were combined with a cost established previously for uncomplicated chickenpox. The estimated yearly overall economic impact of chickenpox in Canada was $122.4 million, with $24.0 million attributable to Ministry of Health costs, assuming an estimated yearly incidence of 346 527 cases and a 0.54% rate of hospitalization for healthy children.
Conclusions. Direct medical costs are the major cost driver in the care of complicated chickenpox. However, in the context of the overall economic burden of the disease, uncomplicated chickenpox is the major cost driver, contributing 89% to the total cost.
- VZV =
- varicella zoster virus •
- CNS =
- central nervous system •
- VZIG =
- varicella zoster immune globulin •
- IMPACT =
- Immunization Monitoring Program Active
Primary infection with varicella zoster virus (VZV) causes chickenpox. Most illnesses are mild; however, some complications including bacterial superinfections and central nervous system (CNS) and pulmonary complications may require management in hospital and sometimes lead to long-term disability and death. Up to 9300 hospitalizations per year result from chickenpox complications and the overall death rate from the disease in the United States is approximately 1 in 40 000.1–5 The Centers for Disease Control and Prevention have estimated that in the United States, varicella was the underlying cause of death in an average of 100 children per year.6 In Canada, a similar death rate (1 in 33 000) has been determined for patients in Ontario.7
The risk of developing complicated and fatal infection is significantly higher among immunocompromised children compared with otherwise healthy children. In the past, 30% to 50% of such children developed disseminated infection, and as many as 10% died.8–12 In recent years, however, the prevention and management of chickenpox among immunocompromised children, especially those with acute leukemia, have become more standard, involving prophylaxis with varicella zoster immune globulin (VZIG) after a known exposure to chickenpox and, if chickenpox develops, admission to hospital for treatment with intravenous acyclovir.
The economic burden of hospitalizations related to chickenpox has been estimated using discharge data or national survey data to calculate an average cost for complications.8–10 Using such methods, Lieu and colleagues9 estimated the per-patient cost of hospitalizations attributable to varicella at $US 7482 for otherwise healthy children, 5 to 9 years of age, with no underlying disease. However, these approaches do not permit an assessment of either the relative cost of care for specific complications or how variations in their prevalence might impact the overall economic burden of illness.
In Canada, no data are available on the cost of illness of chickenpox. In a companion article, we assessed the economic burden of uncomplicated chickenpox defined as acute illness not requiring hospitalization. In the present study, we have determined the per-patient and total treatment costs for complicated chickenpox, defined as requiring hospitalization, according to defined complication subgroups for both previously healthy children as well as for those with leukemia. By combining this cost with the cost for uncomplicated chickenpox, we were able to estimate the overall annual economic burden of the disease in Canada.
MATERIALS AND METHODS
This study was designed to determine both direct and productivity costs associated with the care of complicated cases of chickenpox in Canada. Direct costs included medical and nonmedical resources, and productivity costs included time missed from work and daily activities by the caregivers. Data on costs were derived from three sources. First, samples of previously healthy children and children with leukemia, all with complicated chickenpox as defined above, were selected from the Immunization Monitoring Program Active (IMPACT) database, and additional information on medical resource use in hospital was obtained by review of the medical charts. Secondly, when possible, a telephone interview was conducted with the parents of children in the sample of previously healthy cases to inquire about any hospital admissions at a non-IMPACT center during the year after the original illness; the impact on their well-being (eg, sleep, anxiety); and the economic impact during the course of the child's illness. Finally, previously healthy children admitted to a participating IMPACT hospital for chickenpox or a related complication were enrolled prospectively, and an interview was conducted with the child's caregiver(s) during and within a few weeks after the hospital admission. The study was approved by the ethics review committees of all participating IMPACT centers, and informed consent was obtained from all legal guardians before conducting interviews.
IMPACT is a pediatric hospital-based network funded by Health Canada, designed to collect information on potentially vaccine-related severe adverse events and on serious illness caused by selected pathogens for which childhood vaccines are currently or soon to be available.11 The network includes 11 centers that make up ∼85% of available tertiary-care pediatric beds in Canada and have nearly 90 000 admissions annually. Active surveillance for VZV infections was conducted by the network from January 1, 1991, through March 31, 1996. During this period, trained nurse monitors screened all patients admitted for chickenpox, shingles, or related complications, and determined the association, if any, between the VZV illness and hospital admission. Case finding was enhanced by regular communication with ward staff and infection control personnel and periodic review of medical records with an International Classification of Diseases, 9th Rev, code for VZV infection (052.X or 053.X). A standard form was used to collect data on patient demographics, clinical characteristics of the illness, and hospital course. Of 1323 cases of VZV infection entered into the IMPACT database during the 5-year period of surveillance, 861 (65.1%) had a presenting complaint of chickenpox or an associated complication. Among these children, 488 (56.7%) were considered otherwise healthy, whereas the remaining 373 had some recognized underlying health problem before admission for chickenpox. The latter group included 124 children with active, or a history of, acute leukemia who were considered to be immunocompromised at the time of admission. A detailed description of all cases is being published separately.
Each chickenpox case in the database was subgrouped into 1 of 5 mutually exclusive complication categories: 1) CNS included cases with any listed neurologic problem including encephalitis, cerebellar ataxia, viral meningitis, neuropathy, or seizures; 2) minor infection included cases with a single listed complication of localized secondary bacterial cutaneous or subcutaneous infection; 3) isolated thrombocytopenia included cases with a documented platelet count of <150 × 106/L and no other listed complication; 4) other complications included all cases with one or more listed complications that did not fit one of the definitions above; and 5) primary varicella included cases with chickenpox but no associated complication.
Case Selection From IMPACT Database
A convenience sample of 160 (33%) otherwise healthy children and 40 (32%) children with leukemia was chosen from the IMPACT chickenpox database for determination of direct medical costs. Healthy cases were selected based on total days in hospital at the IMPACT Center and complication category. The length of hospitalization attributable to chickenpox exceeded 7 days for 80 (16.4%) of the 488 healthy cases. To determine whether the average daily medical costs differed according to length of hospitalization, all 80 children who were in hospital for more than 7 days (long-stay group) were selected for review. An additional 80 cases were randomly selected from the remaining 408 children who were in hospital for 7 or fewer days (short-stay group). The randomization was stratified by IMPACT Center and complication category to ensure that each center would have similar numbers of long- and short-stay cases and that the overall complication subgroup mix would be similar to that of the total group of 488. For the group with leukemia, case selection was conducted in a manner: 1) to provide enough cases for a meaningful comparison of the costs of medical care for the 98 (79%) children with primary varicella versus the remaining 26 (21%) with a recognized complication of VZV illness; 2) to assess whether previous VZIG prophylaxis, given to 57 (46%) of the children, impacted the cost of illness; and 3) to control for the possible effect of center variation in management. A total of 20 cases with a complication and 20 cases with primary varicella were chosen.
Data Collection for IMPACT Cases
A standard form was used to collect data from the medical charts regarding the number and type of medical and surgical procedures as well as specialist/subspecialist visits during the original IMPACT hospitalization for chickenpox both for healthy children and for children with leukemia. In addition, for the healthy group only, a similar form was used to record data from the medical records if the patient had been rehospitalized at the IMPACT Center as a result of a continuing complication from chickenpox during the 1-year period after the initial discharge.
Efforts were made to locate and interview the parent or legal guardian of healthy children to assess the days missed from work by employed family members and the impact of the disease on the caregivers. No attempt was made to contact families of children with leukemia for ethical reasons. The families also were asked whether their child had been admitted to a hospital other than the IMPACT Center during the year after discharge from the initial hospitalization. This interview relied on individual recall as a measure of these components during the initial hospitalization or rehospitalization.
Data Collection for Newly Enrolled Cases
This aspect of the study was designed to update illness patterns and management of children hospitalized for chickenpox and to assess family resource consumption (eg, workdays lost, personal expenses) in a prospective manner. For this study, healthy children 9 years of age or younger with complicated chickenpox, hospitalized between June and November 1997, were recruited consecutively from 8 of the IMPACT Centers. The complication categories described for the IMPACT database cases were also used to classify patients recruited prospectively. The relevant medical data were extracted from the patient's chart using a similar form as described above. In addition, a questionnaire was completed with the parents or legal guardian, at the time of the child's hospitalization and after discharge, to collect other resources consumed during the course of the disease. These resources included the number of days missed from school or day care by the patient, the number of days missed from work and time lost from daily activities by the family members, and nonmedical resource consumption (child care, transportation, etc) because of the child's illness.
Cost Association and Structure
Cost valuation for the resources utilized was performed as described in the companion study.13 The per diem cost of pediatric hospitalization was determined from an average of daily inpatient standard ward rates determined by the Ontario and Quebec Ministries of Health (1997/1998) and applied to all hospitalization days. This rate included all inpatient allied health care, laboratory tests, surgical and medical procedures, and medication. Additional technical and professional fees billed directly to the Ministry of Health by physicians were added to the cost of inpatient care.
Total average costs per patient were calculated for the IMPACT database cases and the prospectively enrolled cases from a patient, Ministry of Health, and societal perspective. For cases from the IMPACT database, this was accomplished in three steps. First, the average cost of cases with initial hospitalizations of ≤7 or >7 days for each complication category was determined. An average cost for each complication category was then calculated by weighting these costs according to the probability of children staying in hospital for ≤7 or >7 days. Finally, the overall average cost of treatment of a complicated case of chickenpox was determined, based on the estimated prevalence of each complication category among the database patients. In the prospective analysis, the mean cost for treatment of a hospitalized case was based on an average cost for all patients enrolled in the study. The overall yearly cost of chickenpox in Canada was determined by applying the cost of an uncomplicated case and the average cost of a complicated case to the estimated annual number of uncomplicated and complicated cases of chickenpox.
Probabilities of Specific Chickenpox Complications
Because all IMPACT hospitals provide tertiary care, estimates of the probability of occurrence of each complication subgroup, based on the distribution for the entire database, could be biased by variation in referral patterns. To reduce the possible effect of referral bias, cases for determination of probabilities were limited to those admitted from a defined local community to the IMPACT Center serving that area during 1995, not only for tertiary care but also as the only primary care hospital. In such communities, all children with complicated chickenpox would be admitted to the IMPACT Center. The communities and corresponding IMPACT Centers that met this criterion included Halifax, St John's, Quebec City, Ottawa, Winnipeg, and Calgary. Cases referred from outside the local community were excluded. The resulting case mix, by complication group, for these 6 centers was considered to be the best estimate of the case mix that would occur in all communities.
Sensitivity analyses on the per-patient cost of complicated chickenpox included variation by ±20% of the major cost drivers. In addition, the probabilities of different complications were varied to determine the impact on the per-patient cost of a complicated case. A sensitivity analysis was also conducted on the overall economic impact of chickenpox. This included an analysis on the sensitivity of the total cost of the disease to variation of the overall incidence of complications.
Table 1 shows demographic, disease, and hospital characteristics for the cases chosen for review relative to cases not selected from the database. Among the 408 healthy cases admitted to hospital for ≤7 days, there were no significant differences between the 80 chosen for review and the 328 remaining cases. As a group, the 80 previously healthy cases in hospital for >7 days were significantly older than the short-stay group and had a different distribution of complication type with fewer minor infections or isolated thrombocytopenia. Aside from the longer duration of hospitalization, they also were more likely to be admitted to intensive care, to require mechanical ventilation, and to be treated with acyclovir. Among children with leukemia, the 40 cases selected for review were similar to the remaining 84 cases in terms of sociodemographic variables (Table 1). Clinical variables also were similar, with the exception of the ratio of complications in the selected group (20 of 40 and 26 of 84).
For the prospective study, a total of 26 children were recruited with 3 (11.5%) from Nova Scotia; 6 (23%) from Quebec; 7 (30%) from Ontario; and 10 (38%) from the western provinces of Manitoba (6), Alberta (2), and British Columbia (2).
Sociodemographic data are presented in Table 2 for all healthy patients and their caregivers included in this study. The database group and the cases recruited for the prospective study were comparable in terms of age, gender, ethnicity, and caregiver sociodemographics. For this group of 160 healthy children, 107 caregivers could be contacted and interviewed to collect sociodemographic and resource utilization data. For most of the families interviewed, there were two caregivers living at home with the child (89%) and the primary caregivers were female (94%).
Direct Medical Costs of Complicated Chickenpox
The direct medical resource consumption patterns for each of the mutually exclusive complication categories subgrouped by duration of hospital stay are shown in Table 3. The estimated ratio of cases hospitalized for ≤7 or >7 days for each complication group was based on the distribution observed in the entire IMPACT database (1991–1996) of 488 cases. The ratio was used in conjunction with the unit costs for the resource consumption data from the 160 healthy children to determine an average per-patient cost for each complication (Table 3). The average per-patient cost during the initial hospitalization was highest in the other complications group at $8181, followed by the CNS group at $6612. The day cost of hospitalization contributed >97% to the total treatment cost for all complication categories.
Of the 160 previously healthy children selected, ongoing problems relating to the original varicella illness led to readmission of 11 cases (6.9%), 10 to an IMPACT Center, and 1 to a non-IMPACT Center. Of the children readmitted to an IMPACT Center, 6 were readmitted once, 2 were readmitted twice, 1 had 4, and 1 had 11 readmissions. The average treatment costs for these rehospitalized children varied with the complication category, ranging from $22 604 for the CNS group to $11 302 for the other complications group.
The distribution of the five complication categories used to determine the overall cost of a hospitalized case were 4% primary varicella, 38% minor infection, 12% CNS, 6% isolated thrombocytopenia, and 40% other complications. These figures represent the case mix at the 6 IMPACT Centers, which are the sole providers of both primary and tertiary inpatient care for their communities. By applying these probabilities to the total cost for each complication group, a single value for the average number of resources consumed and the average cost of a healthy complicated case of chickenpox was determined (Table 4). Under these conditions, the average length of initial hospitalization was 6.4 days, and the total average direct cost per patient was $6825. The day cost of hospitalization was the major cost driver, representing 93% of this total cost.
The average resource utilization and costs for the 26 patients recruited prospectively in 1997 are also presented in Table 4. For this group the distribution by complication group was 12 (46%) minor infection, 3 (11.5%) CNS, 3 (11.5%) isolated thrombocytopenia, and 8 (31%) other complications. The mean length of initial hospitalization for all 26 patients was 7.1 days, 0.7 days more than the average stay in the database group.
Productivity Costs of Complicated Chickenpox
Nonmedical resources were collected during the parent interview for all 26 patients recruited prospectively and for 107 of the previously healthy children from the IMPACT database (Table 4). The total combined average number of days missed from work for both caregiver 1 and caregiver 2 in the database group was 8.0 days, similar to the 9.5 recorded prospectively. The caregivers from the prospective group reported an additional total of 53.6 hours lost from daily activities during the child's illness. Similar data were not collected from the IMPACT database group. When unit costs were associated with these resources, the average per-patient cost determined in the database group was $353. In the prospective group, the average per-patient cost of workdays and time lost was $961, with the latter contributing 43% to the total cost.
Direct Medical Costs for Children With Leukemia
For this population, resource utilization data were defined in terms of two parameters: the presence or absence of complications and whether the child had received VZIG therapy (Table 5). The cost of VZIG was not included in the calculation because information on dose was missing. Among the 20 children with complications, those who received VZIG prophylaxis (n = 8) spent an average of 7.3 days in hospital compared with 9.5 days for those who did not receive VZIG (n = 12). The corresponding figures for children with leukemia without complications were 6.1 days with VZIG (n = 10) and 7.3 days without (n = 10). The associated treatment costs indicated that patients with leukemia receiving VZIG prophylaxis had lower costs, specifically, 32% and 19% lower, respectively, in the presence or absence of complications. The cost driver for this population was the day cost of hospitalization, regardless of whether they received VZIG.
Overall Cost of Chickenpox
The overall economic impact of chickenpox in Canada was determined by applying the average per-patient cost of an uncomplicated case13 and that of a complicated case to the yearly incidence of chickenpox (Table 6). To estimate the number of cases of chickenpox in 1 year, we assumed that the yearly number of cases of chickenpox in Canada would equal 95% of the annual birth cohort and that of these cases, 0.54% would require hospitalization.12 On this basis, we estimated that there would be 344 656 uncomplicated and 1871 complicated cases of chickenpox in Canada each year. The number of chickenpox cases in children with leukemia was not considered in the overall cost. Based on these estimates the overall economic impact of chickenpox, from a societal perspective, was $122.4 million per year, 19.6% ($24.0 million) of which was attributable to direct medical costs paid by the Ministry of Health (Table 6). With respect to the direct medical costs, 53.3% was attributable to the cost of the treatment of complicated cases.
Several sensitivity analyses were performed on the cost of a complicated case of chickenpox to determine the impact on the overall economic cost of the disease to society (Table 7). When the cost of hospitalization, the major driver in determining the cost of care of complicated disease, was varied by ±20%, there was little impact on the overall economic burden of chickenpox, with a 1.9% change in the overall cost. In another sensitivity analysis, the probabilities of CNS, other complications, and minor infections were varied, while the overall complication rate was fixed at 0.54%. Therefore, an increase in the incidence of one complication category was assumed to result in a proportional decrease in the incidence of remaining complications. The resulting impact on the overall cost of chickenpox was small and, in most cases, the changes were <1%. Similarly, when the incidence rate of hospitalization was varied to 0.34% and 0.74%, the corresponding change in the overall cost of the disease was ∼2.1%.
This study provides a detailed analysis of the costs associated with hospitalization for chickenpox and associated complications in Canada. The results of the database analysis determined that the average per-patient cost for a complicated case was $6825 from the Ministry of Health perspective and $7060 from the societal perspective. The calculation of the same costs by recruitment of 26 new complicated cases showed an average per-patient cost of $7111 and $8398, respectively, from the Ministry of Health and society perspectives. In this prospective analysis, the societal cost included direct nonmedical expenses to the family such as child care and transportation costs, as well as the cost of time lost by the caregivers for leisure time. The assessment of rehospitalization in the database analysis quantified the economic impact of continuing complications from chickenpox over the 12-month period after the initial hospitalization. The study did reveal that long-term CNS complications have a high cost. Of the 42 selected patients hospitalized with a CNS complication, 3 were rehospitalized within 1 year of the original discharge, with a mean per-patient direct cost of $22 604 for treatment.
The purpose of the prospective recruitment of complicated cases was to compare the length of hospitalization in 1997 to the average length of stay from 1991 to 1996 and to assess more accurately the number of days missed from work by the caregivers, because in the database study this assessment relied on long-term caregiver recall. In the database study, hospitalization was 6.4 days and 8.0 days were lost from work, compared with 7.1 and 9.5 days from the prospective study. For the overall analysis, we chose to use the per-patient cost determined in the database study because this method provided a large number of patient records, allowing for a more representative measurement of the unit cost of all complications. The chart analysis also permitted a comprehensive assessment of the direct medical resources for all complication categories, which included the cost of rehospitalization but did not include the cost of family expenses and caregiver time lost. As a result, we may have underestimated the true economic burden of complicated disease as these additional costs were not included. In the prospective study, the average per-patient costs for personal expenses and time lost were $325 and $550, respectively, adding a total of $875 to the per-patient cost of complicated cases. If these two resources are considered in the total yearly economic burden of complicated cases, there is an additional expense of $1.6 million for 1871 complicated cases, which increases the total annual economic burden to $124.0 million.
The overall yearly economic burden of chickenpox (uncomplicated and complicated cases) in Canada was estimated at $122.4 million, from the society perspective, with uncomplicated cases contributing 89.2% to this total cost. The overall cost to the Ministry of Health was $24.0 million (20% overall), with a relatively balanced distribution of medical costs associated with outpatient care (uncomplicated cases, 47%) and inpatient care (complicated cases, 53%). Therefore, although the rate of hospitalization attributable to chickenpox in Canadian children is low, estimated at 1871 cases per year, the economic impact of $12.8 million is substantial, given the daily cost of hospitalization. If the cost of chickenpox ($122.4 million) is distributed across all cases of the disease (ie, 95% of the birth cohort), the cost per individual case of chickenpox is $353.1, with $32.4 (9.2%) for outpatient treatment; $36.9 (10.4%) for inpatient treatment; and $284.3 (80.5%) for costs related to days missed from work, leisure time, and personal expenses. These costs represent a recurring yearly burden because in an unvaccinated population, ∼95% of the birth cohort are infected and will incur these costs each year.
Several studies, primarily in the United States, also have estimated the total cost of chickenpox. Using a 30-year decision model, Preblud10 estimated that for 3.2 million cases each year in the United States, the annual societal cost was ∼$US 400 million, of which medical costs accounted for 4%, with the remainder primarily associated with days missed from work by the caregivers. In a more recent study, Lieu and colleagues9 estimated that for a hypothetical birth cohort in the United States of nearly 4 million, direct medical costs contributed 17% of the total estimated yearly burden of $US 439 million attributable to chickenpox. The numbers in the Lieu et al paper are comparable with the figures collected in the present study in which direct medical costs paid by the Ministry of Health accounted for 20% of the total economic burden.
In addition to personal expenses for the family, there are also intangible costs associated with chickenpox including the quality of life of the child and the caregivers. In this study, we conducted a pilot assessment of the well-being of the caregiver for both the database and the prospective groups of previously healthy children. Greater than 60% of the caregivers in both groups reported that their sleep and anxiety levels were severely affected during the child's illness.
The analysis of the 40 children with leukemia revealed that the length of initial hospitalization and the average direct medical costs were similar to those determined for healthy children with chickenpox. Treatment costs for children with leukemia who received VZIG prophylaxis were ∼20% less than costs for those children who did not receive VZIG. Because this analysis included neither the actual costs of VZIG prophylaxis for hospitalized cases nor the costs of prophylaxis for the children who were exposed but did not develop chickenpox, it is difficult to draw any concrete conclusions regarding the cost-effectiveness of VZIG. For these reasons, we chose to base the overall annual cost of chickenpox in Canada on the cost of a healthy child, because it would be difficult to estimate the annual number of cases in children with leukemia or other immunocompromising conditions.
One of the limitations to this study was that the cost of complicated disease was based on a database assessment of patient records dating to 1991, which may not be a true reflection of contemporary treatment patterns. However, a majority of the cases were recruited in 1995 and 1996. In addition, although somewhat limited in patient numbers, the prospective study derived similar per-patient costs of complicated disease in 1997, evidence that the database analysis provided an accurate assessment of chickenpox treatment practices. Another limitation may be the absence of an assessment of the long-term economic impact of the disease, which may have underestimated the total lifetime cost of complicated chickenpox. Some of the complications of chickenpox, especially encephalitis, can result in long-term medical problems, with associated direct medical and productivity costs.9 ,14 However, in this study, only 1st-year costs of hospitalization attributable to chickenpox complications were included in the overall economic impact, and the 6.3% of patients rehospitalized contributed $325 to the direct cost of a complicated case. In addition, mortality, although a small component in comparison with the total number of chickenpox cases, nevertheless can impose a large economic burden (death at a young age). Finally, our estimate of the overall yearly cost excludes the direct and productivity costs involved in dealing with inadvertent exposure of patients and health care workers to chickenpox in hospital. In a US study, Weber and associates15 have shown that VZV exposure under these conditions can have a significant economic impact. Because of these cost limitations, our overall annual cost to society of $122.4 million may be a conservative estimate.
The economic burden of chickenpox is substantial and comparable with other childhood diseases such as measles, mumps, and rubella.16 For example, per-patient treatment costs of uncomplicated measles in Canada have been estimated at $24 and $299, respectively, from the Ministry of Health and societal perspectives, values that are similar to the treatment costs defined for chickenpox in the present study.16 Childhood vaccination against chickenpox has been shown to be clinically effective and economically viable, with societal benefit cost ratios ranging from 6.9:1 to 5.4:19 ,10 calculated for US vaccination programs. In addition, Huse and co-workers(1994)8 estimated that a US chickenpox vaccination program would yield an expected societal economic benefit of $US 66.5 (1993) per vaccinated individual. The results from the present study will provide baseline data to evaluate the economic impact of a vaccination program in Canada from both a Ministry of Health and a societal perspective.
This study was funded by Merck Frosst Canada.
We thank the study nurses and research assistants who helped make this study possible: Ardith Ambrose, Claude Belleville, Francine Binder, Helen Etherington, Marie-France Gagnon, Hélène Goulet, Susan Grant, Catherine Guimond, Marilyn Harvey, Helen Heurter, Maureen L. Hutmacher, Lorraine Piché-Walker, Ann Roth, Heather Samson, Darrell Tan, and Lindsay Thompson. We also thank Irene Dehem for her assistance with the analysis.
- Received September 14, 1998.
- Accepted November 30, 1998.
Reprint requests to (C.F.) Quintiles Canada, 100 Alexis-Nihon, Suite 800, Ville St-Laurent, Québec H4M 2P4. E-mail:
↵FNa Members of IMPACT: Scott Halperin, MD, IWK Grace Health Center, Halifax; Elaine Wang, MD, The Hospital for Sick Children, Toronto; Marc Lebel, MD, Hôpital Sainte-Justine, Montreal; David Scheifele, MD, Vaccine Evaluation Center, Vancouver; Noni MacDonald, MD, Children's Hospital of Eastern Ontario, Ottawa; Elaine Mills, MD, Montreal Children's Hospital, Montreal; Robert Morris, MD, Janeway Child Health Center, St-John's; Pierre Déry, MD, Centre Hospitalier Universitaire de Québec, Québec; Taj Jadavji, MD, Alberta Children's Hospital, Calgary; Wendy Vaudry, MD, WC MacKenzie Health Sciences Center, Edmonton; Philippe Duclos, PhD, Bureau of Infectious Disease (at the time of study), Ottawa; Gilles DeLage, MD, Canadian Paediatric Society, Ottawa.
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- Copyright © 1999 American Academy of Pediatrics