CatastROphiC expenditure rates and barriers fOr treatment aDherence In patients with colorectaL cancEr in India: CROCODILE study protocol.

AIMS Little is known about colorectal cancer treatment delivery in India and associated costs. The aim of this study is to identify financial and non-financial barriers for colorectal cancer treatment adherence in India. METHODS CROCODILE is a mixed-methods with a quantitative and a qualitative workstream. The quantitative workstream will be a prospective cohort study to assess treatment adherence and catastrophic expenditure rates among patients with colorectal cancer in India. Consecutive, newly diagnosed patients with histopathologically proven colorectal cancer will be included from five tertiary hospitals in India. Catastrophic expenditure will be defined as treatment cost being higher than 40% of non-subsistence annual household income. Treatment costs will include medical, non-medical and indirect expenses. Income assessment will be compared between three methods: patient-reported income, the International Wealth Index, and the Gapminder tool. The qualitative workstream will explore colorectal cancer patients' and professionals' views and experiences about barriers and facilitators for treatment adherence. Individual semi-structured interviews with three to five patients and cancer care professionals in each centre will be performed. An analytical framework will be developed to perform the analysis, through a combined approach (deductive and inductive). The results will be triangulated with the quantitative workstream for mutual knowledge enrichment. DISCUSSION The CROCODILE study will identify barriers and facilitators for colorectal cancer delivery in India, influencing research and policy decisions. It will explore feasibility of data collection on patient level costs and income, to inform future economic evaluations in cancer and surgical care.