Outcomes of hypercalcemia of malignancy in patients with solid cancer: a national inpatient analysis

Hypercalcemia of malignancy (HCM) is present in one-third of cancer patients and is associated with a significant mortality risk of 50% within 1 month of diagnosis. We aimed to study the impact and outcomes of HCM in hospitalized patients with solid cancer. We analyzed data captured in the National Inpatient Sample database of the Agency of Healthcare Research and Quality. The study included all hospitalizations in adult solid cancer patients between January 2012 and September 2015 with hypercalcemia. All encounters associated with HCM were identified using the ICD-9 code (275.42) for hypercalcemia. Encounters with other known causes of hypercalcemia were excluded. The co-primary outcomes were incidence of HCM and inpatient mortality. During the study period, 7,501,209 hospitalizations met our inclusion criteria. Approximately 1.7% (n = 126,875) of these hospitalizations were related to HCM. This corresponds to approximately 1 in 59 solid malignancy associated hospitalizations. The mean age of patients with HCM was 65.7 years; 49% were females; 69% were Caucasians; 73% had metastatic disease and 22% received a palliative care consult. When compared to those without HCM, those hospitalized with HCM had a significantly longer mean hospital length of stay (7.3 days vs. 5.6 days, p < 0.001), higher inpatient mortality (12.3% vs. 5.5%, adjusted OR 1.76 (95% CI 1.69-1.84), p < 0·0001), and a greater likelihood of discharge to other facilities (27.4% vs. 16.2%, p < 0.0001). Although HCM accounts for < 2% of all hospitalizations in patients with solid cancer, those with HCM display higher mortality than those without HCM.