About the Database

What's Included in the Database
What's Included in a Citation
Development of the Database
 
What's Included in the Database
The database contains over 2,000 citations from January 1, 1980 to December 31, 2008 and continues to be updated. Consistent with use in allocation decision-making, only full economic evaluations were accepted for inclusion, i.e. a comparator existed and descriptions of both costs and health outcomes were present. The economic evaluation did not have to be the primary objective of the study to be eligible.

The inclusion criteria required that the study contain original analysis and include the evaluation of an intervention, such as a medical or surgical treatment, a program, a service, or a new process; that the intervention was directed at the paediatric population including neonates, infants, children, or adolescents less than 19 years; that if interventions were aimed at pregnant women or mothers, outcomes were measured in offspring; that the comparator was either real or implied, such as in a pre- and post-intervention, or a 'do nothing' or 'usual care' approach; that a health outcome, intermediate or final, was reported and that costs were measured and reported. Randomized controlled trials and observational studies were eligible as were modelling studies and meta-analyses if they included novel data aggregation and new analyses. Publications written in languages other than English were accepted and entered into the database if an English abstract was available.

Cost analyses, cost descriptions and cost of illness studies or studies where a specific intervention was not evaluated were excluded. Interventions consisting of a continuous quality improvement process or a new operating procedure or policy were excluded as were studies where costs were not quantified. To restrict the database to original, full economic evaluations, abstracts from conference proceedings, methodological papers, papers without original analyses, policy statements, case studies or reports, letters, editorials or notes were excluded.

   
What's Included in a Citation
Together with standard citation information, the PEDE database provides the following additional information for each record:
 

• Target population
• Population category
• Disease class: ICD-9-CM (up to 2003) or ICD-10 (2004 and later)
• Age group
• Experimental intervention
• Intervention category
• Primary health outcome
• Analytical technique

 
The ICD-9-CM classifies all disease according to major organ systems, including:

• Infectious and Parasitic Disease
• Neoplasms
• Endocrine, Nutritional and Metabolic Diseases, and Immunity Disorders
• Diseases of the Blood and Blood-Forming Organs
• Mental Disorders
• Diseases of the Nervous System and Sense Organs
• Diseases of the Circulatory System
• Diseases of the Respiratory System
• Diseases of the Digestive System
• Diseases of the Genitourinary System
• Complications of Pregnancy, Childbirth, and the Puerperium
• Diseases of the Musculoskeletal System and Connective Tissue
• Congenital Anomalies
• Certain Conditions Originating in the Perinatal Period
• Symptoms, Signs and Ill-defined Conditions
• Injury and Poisoning

 
The ICD-10 classifies all disease according to major organ systems, including:

• Certain infectious and parasitic diseases
• Neoplasms
• Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism
• Endocrine, nutritional and metabolic diseases
• Mental and behavioural disorders
• Diseases of the nervous system
• Diseases of the eye and adnexa
• Diseases of the ear and mastoid process
• Diseases of the circulatory system
• Diseases of the respiratory system
• Diseases of the digestive system
• Diseases of the skin and subcutaneous tissue
• Diseases of the musculoskeletal system and connective tissue
• Diseases of the genitourinary system
• Pregnancy, childbirth and the puerperium
• Certain conditions originating in the perinatal period
• Congenital malformations, deformations and chromosomal abnormalities
• Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
• Injury, poisoning and certain other consequences of external causes
• External causes of morbidity and mortality
• Factors influencing health status and contact with health services
• Codes for special purposes

With regard to antenatal care or family planning interventions, pregnancy was not considered a state of ill health. Thus non-disease categories labeled "General Health" and "Dental Health" were created for these and other interventions related to basic health services.

 
Age Groups were created as follows:

• Perinates: the antenatal period of the fetus or premature newborn, up to 7 days of life
• Neonates: newborns, until the first month of age
• Infants: 1 month to 1 year of age
• Children: 1 to 12 years of age
• Adolescents: 13 to 18 years of age

   
Each experimental intervention was categorized as follows:

• Prevention (specified as Health or Dental): An intervention for the prevention of illness or disease. There was no distinction made between primary, secondary, or tertiary prevention.
• Treatment (specified as Health or Dental): An intervention administered directly to the patient for the cure or amelioration of a disease or condition.
• Program (specified as Health or Dental): An organization or organizational unit, clinic, department, or health system.
• Surgical: Operative procedures used to correct deformities and defects, repair injuries, diagnose, or cure certain diseases.
• Educational: An educational process or program designed for the improvement and maintenance of health.
• Health care delivery: A process, service, tool, test or treatment pathway.
• Detection: Tests used to screen for disease or the potential of developing disease.
• Diagnosis: The use of clinical tests to confirm the cause of illness.
• Psychological: Interventions used for normal and abnormal mental health conditions.

• Cost-utility analysis (CUA)
• Cost-benefit analysis (CBA)
• Cost-effectiveness analysis (CEA)
• Cost-minimization analysis (CMA)

   
Development of the Database
The following stages were used to create the PEDE Database: Development of the Search Strategy, Eligibility Review, Data Extraction and Reliability Assessment.
 
Development of the Search Strategy
Citations were derived from multiple sources such as electronic citation databases, Web sites, electronic communications and print publications.

A search program was written for each citation database, including Medline, CINAHL, HealthStar, Cancerlit, EMBASE, IPA, EconLit, PubMed (PreMedline), Current Contents (ScanDoc), the Cochrane Collection and the University of York's three databases, NHS EED, DARE and HTA. Search programs were designed to achieve high sensitivity (no false negatives). In addition to the above citation databases, Web sites of government agencies, technology assessment organizations, research institutions, universities and other groups involved with health economics, health policy, health services research and outcomes research were searched for relevant unpublished reports and working papers. Relevant electronic journals and newsletters, print newsletters, reports, monographs and text books were also reviewed.
 
Eligibility Review
The citation abstracts that were extracted by the search strategy were evaluated for eligibility. Only full economic evaluations were accepted, i.e. a comparator existed and descriptions of both costs and health outcomes were present. The economic evaluation did not have to be the primary objective of the study to be eligible. Abstracts of uncertain eligibility were assessed by a second researcher.
 
Data Extraction
Specific information relevant to health economic evaluation were extracted and entered into the PEDE database from the eligible citations, including, journal name, target population, International Classification of Diseases, 9th revision, Clinical Modification (ICD-9-CM) disease class, age group, intervention, primary outcome and analytical technique.

The following categories were created to reflect the types of interventions encountered: prevention, treatment, program (organization or organizational unit, clinic, department, or health system), surgical, educational, health care delivery (process, service, tool or treatment pathway), detection (tests used to screen for disease or the potential of developing disease), diagnosis (the use of clinical tests to confirm the cause of illness) or psychological.
 
Reliability Assessment
Excellent inter-rater and test-retest reliability assessments were demonstrated for the citation selection process. The percent observed inter-rater agreement was 0.96 and the kappa coefficient, representing chance-adjusted agreement, was 0.91, representing almost perfect reliability. Test-retest reliability resulted in a kappa coefficient equal to 0.95.