Epidemiology of childhood cancer in a section of the private health sector of South Africa

Abstract

The study aimed at determining the incidence, prevalence and trends of childhood cancers over time, as well as identifying the common coexisting conditions in children and adolescents on treatment for cancer in the private health sector of South Africa. A literature review, aimed at describing the types and classification of childhood cancer, elucidating the risk factors associated with childhood cancer, and identifying the treatment options, coexisting conditions and the complications of cancer and its treatment in children was carried out. The empirical investigation, utilising retrospective medicines claims data spanning the period of January 2008 to December 2017, obtained from a Pharmaceutical Benefit Management (PBM) company, followed a quantitative, descriptive, cross-sectional approach. The objectives of the empirical study were to: 1. Determine the incidence, prevalence and trends over time of childhood cancers in children younger than 19 years, stratified according to age group, gender, type of malignancy and geographic area. 2. Identify the common coexisting conditions in children and adolescents with cancer on the database. The study population was categorised into five age groups, namely <1, 1-4, 5-9, 10-14 and 15<19 years using the age at last birthday on the database as the reference date. The first objective was addressed in Manuscript one. Patients with International Classification of Diseases and Related Health Problems, 10th Revision (ICD-10) codes C00 to C97 for cancer in conjunction with claims for medicines reimbursed from patients’ oncology benefit were selected for this study. Over the 10-year period, a total of 173 patients with cancer (0.01% of children younger than 19 years on the database) were identified. This translated into an age-standardised incidence rate (ASR) of 82.3 cases per million persons. The mean age of the study population was 10.0 ± 5.4 (95% CI, 9.2-10.9) years. Age-specific incidence rates were highest in 15<19 years’ age group (112.8 cases per million persons) and lowest in the <1 year age group (13.2 cases per million persons). Higher incidence rates were estimated for males as compared to females, with ASRs of 112.3 and 51.9 cases per million persons, respectively. Leukaemias, lymphomas and central nervous system (CNS) neoplasms were the most frequently occurring cancers, with overall ASRs of 32.6, 11.7 and 9.1 cases per million persons, respectively. Hepatic tumours were the least occurring cancers (ASR of 0.5 cases per million persons). The highest incidence rate of cancer was observed in the KwaZulu-Natal province (193.4 cases per million persons) followed by Gauteng (102.3 cases per million children). This may, however, not necessarily indicate a high incidence of cancers in those provinces since postal codes of prescribers were used as a proxy for geographic location. No new cases in the Eastern Cape, Mpumalanga, and Northern Cape provinces were identified on the database during the study period. Incidence rates of all childhood cancers combined decreased from 76.7 cases per million persons in 2008 to 58.2 cases per million persons in 2017. The prevalence of childhood cancers increased from 9 cases per 100 000 children in 2008 to 13.3 cases per 100 000 children in 2017. Leukaemias were consistently the most prevalent diagnostic group during the study period, with prevalence increasing from 25.0% of all cancer diagnostic groups in 2008 to 43.8% in 2017. With the exception of 2008, cancers were more prevalent in males as compared to females from 2009 to 2017. Findings of the investigation into the coexisting conditions in children undergoing treatment for cancers were presented in manuscript two. A total of 2 631 non-cytotoxic medicine items were claimed for children and adolescents on cancer chemotherapy during the study period. Approximately 83% (n = 2 272) of these medicine items were claimed under non-specific diagnostic codes which included codes for repeat prescriptions, failure of patient or clinician to disclose clinical information, and encountering health services in unspecified conditions. A drug utilisation 90% (DU90) of medicine items claimed under non-specific diagnostic codes, using the Monthly Index of Medical Specialties (MIMS) classification indicated that antimicrobials, respiratory agents, analgesics, ear, nose and throat agents, gastrointestinal tract agents, central nervous system agents, autacoids, dermatological agents, endocrine agents, herbal preparations, musculoskeletal agents and anaesthetics, made up the top 90% medicines with these diagnostic codes. Diagnostic codes for diseases of the respiratory system, diseases of the gastrointestinal tract and disorders of the skin were associated with 7.15%, 1.60%, 0.95% and 0.91% of the medicine items, respectively. Antimicrobial agents were found to be the most frequently claimed medicines (17.4%, n = 458), followed by respiratory agents, (13.9%, n = 366) and analgesics (10.6%, n = 280), among all medicine claims. Overall, 82.1% (n = 2 160) of the medicine items claimed over the study period were reimbursed from patients’ acute benefits and 0.5% (n = 13) were reimbursed from patients’ chronic benefits. In conclusion, this study provided an insight into the epidemiological trends of cancers in children and adolescents in a section of the South African private health sector, with specific reference to trends by gender, age group, malignancy type and geographic area. Coexisting conditions in children and adolescents with cancer were also determined and results indicated that the majority of these coexisting conditions were acute rather than chronic.