Social influence on 5-year survival in a longitudinal chemotherapy ward co-presence network

Chemotherapy is often administered in openly designed hospital wards, where there is the possibility of social influence on health between patients. Previous research has found evidence that cancer patients’ health is impacted by social relationships; however, social influence has not been examined in patients while receiving treatment in a chemotherapy ward. In the current paper, we investigate the influence of co-presence vis-a`-vis cancer patient outcomes on 5-year survival in a chemotherapy ward. Using data on 4,691 cancer patients undergoing chemotherapy in Oxfordshire, United Kingdom, we construct a network of patients where edges between patients equal the Jaccard index of co-presence in the ward. Patients averaged 59.8 years of age, and 44% were male. We count the total Jaccard-weighted person-hours of overlap with focal patients’ immediate neighbors or those two nodes away who finish their chemotherapy cycle and survive 5 years or die within 5 years. Generalized estimating equations were used to evaluate the effect of neighbors’ outcomes on focal patient’s 5-year mortality. Each 1,000-unit increase in Jaccard-weighted person-hours (e.g., a hypothetical focal patient in the ward for 50 hours co-present with 100 patients, all with Jaccard indices of 0.2) with a patient dying within 5 years increases a patient’s mortality odds by 42% (β = 0.357, CI:0.204, 0.510). Each 1,000-unit increase in Jaccard-weighted person-hours with a patient surviving 5 years reduces a patient’s odds of dying by 30% (β = −0.344, CI:−0.538,0.149). Our results suggest that social influence occurs in chemotherapy wards, which may need to be taken into account in chemotherapy delivery.