Trends in admission prevalence,illness severity and survival of haematological patients treated in Dutch intensive care units

Purpose

To explore trends over time in admission prevalence and (risk-adjusted) mortality of critically ill haematological patients and compare these trends to those of several subgroups of patients admitted to the medical intensive care unit (medical ICU patients).

Methods

A total of 1,741 haematological and 60,954 non-haematological patients admitted to the medical ICU were analysed. Trends over time and differences between two subgroups of haematological medical ICU patients and four subgroups of non-haematological medical ICU patients were assessed, as well as the influence of leukocytopenia.

Results

The proportion of haematological patients among all medical ICU patients increased over time [odds ratio (OR) 1.06; 95 % confidence interval (CI) 1.03–1.10 per year; p < 0.001]. Risk-adjusted mortality was significantly higher for haematological patients admitted to the ICU with white blood cell (WBC) counts of <1.0 × 10⁹/L (47 %; 95 % CI 41–54 %) and ≥1.0 × 10⁹/L (45 %; 95 % CI 42–49 %), respectively, than for patients admitted with chronic heart failure (27 %; 95 % CI 26–28 %) and with chronic liver cirrhosis (38 %; 95 % CI 35–42 %), but was not significantly different from patients admitted with solid tumours (40 %; 95 % CI 36–45 %). Over the years, the risk-adjusted hospital mortality rate significantly decreased in both the haematological and non-haematological group with an OR of 0.93 (95 % CI 0.92–0.95) per year. After correction for case-mix using the APACHE-II score (with WBC omitted), a WBC <1.0 × 10⁹/L was not a predictor of mortality in haematological patients (OR 0.86; 95 % CI 0.46–1.64; p = 0.65). We found no case–volume effect on mortality for haematological ICU patients.

Conclusions

An increasing number of haematological patients are being admitted to Dutch ICUs. While mortality is significantly higher in this group of medical ICU patients than in subgroups of non-haematological ones, the former show a similar decrease in raw and risk-adjusted mortality rate over time, while leukocytopenia is not a predictor of mortality. These results suggest that haematological ICU patients have benefitted from improved intensive care support during the last decade.