Characteristics of the patients with cancer and without cancer
During the study period, there were 38,508 patients whose age were older than 18 years admitted to ICUs in the Beth Israel Deaconess Medical Center in Boston, MA, USA between 2001 and 2012, of whom 16,715 (54.7%) were male. The median age was 65 years (IQR, 52–77),and 8,308 (21.8%) had an underlying malignancy diagnosis. Table 1 gives patient characteristics for admissions to ICU with and without a diagnosis of malignancy before and after PSM. ICU patients with cancer tended to be older than patients without cancer with median (IQR) age 70 (60–79) VS 63 (50–77) years (P < 0.001). The population without cancer admitted to ICU as an emergency was 85.9% (25,993 of 30,200 patients) in contrast to 78.1% (6,485 of 8,308 patients) of the population with cancer. Compared with patients with noncancer, patients with cancer were more likely to be admitted by surgical intensive care unit (SICU) (21.5% VS 15.2%) and medical intensive care unit (MICU) (42.0% VS 33.6%). The percentage of the noncancer patients in coronary care unit (CCU), cardiac surgery recovery unit (CSRU) and traumatic surgical intensive care unit (TSICU) were more than that of cancer patients. The admission reasons were otherwise similar between the cancer and noncancer groups with cardiovascular dysfunction, liver disorder, mental disorder, renal disorder, respiratory dysfunction, and coagulation dysfunction. Cancer patients tend to have high critical illness score compared with noncancer patients, SAPSII [39(26–46) VS 31(23–41), P < 0.001], APSIII [40(30–53) VS 37(27–51), P < 0.001]. The Elixhauser comorbidity index score of cancer patients was also significantly higher than noncancer patients [9(2–17) VS 3(0–9), P < 0.001]. Respiratory support was the most common mode of support for both the cancer and noncancer groups at 40.3% (3,351 of 8,308 patients) and 47.2% (14,262 of 30,200 patients), respectively. Cardiovascular support was provided to 27.0% of the cancer group (2,240 of 8,308 patients) and 30.2% of the noncancer group (9,114 of 30,200 patients). Renal replacement therapy was not commonly provided in either group, but those patients in the cancer group had a lower prevalence of RRT [147 of 8,308 patients (1.8%)] when compared with the noncancer group [889 of 30,200 patients (2.9%), P < 0.001]. Patients with cancers were more likely to have a higher frequency of infection (42.7% VS 38.6%, P < 0.001) and sepsis (7.8% VS 6.5%, P < 0.001). After the propensity scores matched using 1:1, the covariates of the cancer group and noncancer group were balanced with a standard difference less than 5% (Fig. 2).
Table 1
Comparison of variables between Intensive care patients with cancer and without cancer before and after propensity score matched analysis
Variable | ALL | Patients before PSM | | Patients after PSM |
| N = 38,508 | Noncancer(N = 30,200) | Cancer (N = 8,308) | P Value | SDD | | Noncancer N = 7,474 | Cancer N = 7,474 | P Value | SDD |
Age, median (IQR),Y | 65(52–77) | 63(50–77) | 70(60–79) | < 0.001 | 44.2 | | 72(59–81) | 69(59–79) | 1.000 | -3.3 |
Gender, No. (%) | | | | 0.545 | 0.8 | | | | 0.921 | 0 |
Female | 16,715(43.4) | 13,133(43.5) | 3,582(43.1) | | 3,276(43.8) | 3,282(43.9) |
Male | 21,783(56.6) | 17,067(56.5) | 4,726(56.8) | | 4,198(56.2) | 4,192(56.1) |
Ethnicity, No. (%) | | | | < 0.001 | 11.1 | | | | 0.829 | 1.6 |
Black | 2,949 (7.7) | 2,404(8.0) | 545(6.6) | | 531(7.1) | 505(6.8) |
Asian | 911 (2.4) | 667(2.2) | 244(2.9) | | 195(2.6) | 207(2.8) |
White | 27,468 (71.3) | 21,035(69.7) | 6,433(77.4) | | 5,749(76.9) | 5,735(76.7) |
Hispanic | 1,254 (3.3) | 1,095(3.6) | 159(1.9) | | 154(2.1) | 154(2.1) |
Other | 5,926 (15.4) | 4,999(16.6) | 927(11.2) | | 845(11.3) | 873(11.7) |
ICU type, No. (%) | | | | < 0.001 | 27.7 | | | | 0.717 | 1.7 |
SICU | 6,366(16.5) | 4,578(15.2) | 1,788(21.5) | | 1,528(20.4) | 1,499(20.1) |
MICU | 1,3634(35.4) | 10,148(33.6) | 3,486(42.0) | | 3,090(41.3) | 3,064(41.0) |
CCU | 5,673(14.7) | 4,728(16.7) | 945(11.4) | | 906(12.1) | 920(12.3) |
CSRU | 7,606(19.8) | 6,378(21.1) | 1,228(14.8) | | 1,215(16.3) | 1,207(16.2) |
TSICU | 5,229(13.6) | 4,368(14.5) | 861(10.4) | | 735(9.8) | 784(10.5) |
Admission group, No. (%) | | | | < 0.001 | -20.2 | | | | 0.764 | -0.4 |
Elective | 6,090(15.8) | 4,267(14.1) | 1,823(21.9) | | 1,465(19.6) | 1,467(19.6) |
Emergency | 32,418(84.2) | 25,993(85.9) | 6,485(78.1) | | 6,594(80.4) | 7,294(80.4) |
Admission reasons, No. (%) | | | | < 0.001 | -7.0 | | | | 0.860 | 1.4 |
Cardiovascular | 17,528(45.5) | 13,726(45.5) | 3,802(45.8) | | 3,419(45.8) | 3,416(45.7) |
Liver | 1,312(3.4) | 903(3.0) | 409(4.9) | | 330(4.4) | 328(4.4) |
Mental | 4,118(10.7) | 3,300(10.9) | 818(9.9) | | 783(10.5) | 771(10.3) |
Renal | 4,753(12.3) | 3,686(12.2) | 1,067(12.8) | | 1,011(13.6) | 970(13.0) |
Respiratory | 6,905(18.0) | 5,478(18.2) | 1,427(17.2) | | 1,239(16.6) | 1,288(17.2) |
Coagulation | 1,671(4.3) | 1,257(4.2) | 414(5.0) | | 366(4.9) | 356(4.8) | |
Other | 2,221(5.8) | 1,850(6.1) | 371(4.5) | | 326(4.4) | 345(4.6) |
SOFA, median (IQR) | 3 (2–5) | 3 (2–5) | 3(2–5) | 0.001 | 2.5 | | 3(2–6) | 3(2–6) | 0.622 | -0.9 |
SAPS II, median (IQR) | 24(33–92) | 31(23–41) | 39(26–46) | < 0.001 | 36.6 | | 36(28–46) | 36(28–44) | 0.490 | -1.4 |
APS III, median (IQR) | 38(25–51) | 37(27–51) | 40(30–53) | < 0.001 | 11.4 | | 40(29–54) | 39(30–52) | 0.462 | -2.0 |
LODS, median (IQR) | 3(2–5) | 3(2–5) | 3(2–5) | < 0.001 | 5.7 | | 4(2–5) | 3(2–5) | 1.00 | -0.5 |
OASIS, median (IQR) | 30(25–37) | 30(25–37) | 30(25–37) | 0.293 | 1.2 | | 31(25–37) | 31(25–37) | 0.09 | -1.4 |
Elixhause comorbidity, median (IQR) | 4 (0–12) | 3(0–9) | 9(2–17) | < 0.001 | 56.0 | | 9(0–16) | 8(0–15) | 0.933 | -0.4 |
RRT on first day, No. (%) | 1,036(2.7) | 889(2.9) | 147(1.8) | < 0.001 | -7.7 | | 154(2.1) | 145(1.9) | 0.599 | -0.7 |
MV on first day, No. (%) | 17,613(45.7) | 14,262(47.2) | 3,351(40.3) | < 0.001 | -13.9 | | 3,051(40.8) | 3,084(41.3) | 0.583 | 1.1 |
Vasopressor administration on first day, No. (%) | 11,354(29.5) | 9,114(30.2) | 2,240(27.0) | < 0.001 | -7.1 | | 2,094(28.0) | 2,076(27.8) | 0.743 | -1.1 |
Sepsis, No. (%) | 2,601(6.8) | 1,951(6.5) | 650(7.8) | < 0.001 | 5.3 | | 603(8.1) | 783(7.8) | 0.545 | -1.4 |
Infection, No. (%) | 15,192(39.5) | 11,641(38.6) | 3,551(42.7) | < 0.001 | 8.5 | | 3,164(42.3) | 2,196(42.8) | 0.597 | 1.1 |
Abbreviations: Intensive care unit, ICU; the standardized differences, SDD; propensity score matching, PSM; IQR, 25–75% interquartile range; Sequential Organ Failure Assessment, SOFA; Simplified Acute Physiology Score II, SAPSII; Logistic Organ Dysfunction Score, LODS; Oxford Acute Severity of Illness Score, OASIS; Acute Physiology Score, APSIII; Surgical intensive care unit, SICU; Medical intensive care unit, MICU; Coronary care unit, CCU; Cardiac surgery recovery unit, CSRU; Traumatic surgical intensive care unit, TSICU; mechanical ventilation, MV; renal replacement therapy, RRT. |
Outcomes of patients with cancer and without cancer before and after propensity score matched analysis (Table 2)
Table 2
Outcomes of patients with cancer and without cancer before and after propensity score matched analysis
Outcome | ALL | Patients before PSM | | Patients after PSM |
| n = 38,508 | Noncancer N = 30,200 | Cancer N = 8,308 | P Value | | Noncancer N = 7,474 | Cancer N = 7,474 | P Value |
LOS of ICU, median (IQR), d | 2.1(1.2–4.1) | 2.1 (1.2–4.1) | 2.1(1.2–3.9) | < 0.001 | | 2.1(1.2–4.2) | 2.1(1.2–3.9) | < 0.001 |
LOS of Hospital, median (IQR), d | 6.9(4.0-11.9) | 6.8(4.0-11.8) | 7.3(4.4–12.2) | < 0.001 | | 7.1(4.2–12.6) | 7.2(4.3–11.9) | 0.774 |
28-day survive, % (95%CI) | 86.6(86.2–86.9) | 88.0(87.6–88.4) | 81.3(80.5–82.1) | < 0.001 | | 84.9(84.0-85.7) | 82.3(81.4–83.1) | < 0.001 |
90-day survive, % (95%CI) | 81.8(81.4–82.2) | 84.3(83.9–84.7) | 72.9(72.0-73.9) | < 0.001 | | 79.2(78.3–80.1) | 74.3(73.3–75.3) | < 0.001 |
365-day survive, % (95%CI) | 74.9(74.4–75.3) | 79.1(78.7–79.6) | 59.3(58.2–60.3) | < 0.001 | | 72.7(71.7–73.7) | 61.4(60.3–62.5) | < 0.001 |
1,095-day survive, % (95%CI) | 67.3(66.9–67.8) | 72.6(72.1–73.1) | 48.3(47.3–49.4) | < 0.001 | | 64.6(63.5–65.7) | 50.4(49.3–51.6) | < 0.001 |
Abbreviations: LOS, length of stay; Intensive care unit, ICU; propensity score matching, PSM; IQR, 25–75% interquartile range. |
In the crude model, 28-day, 90-day, 365-day and 1095-day survive rate of noncancer group were 88.0%, 84.3%, 79.1% and 72.6%, respectively, which were higher than the cancer group with 81.3%, 72.9%, 59.3% and 48.3%, respectively. After PSM, the noncancer group still had a significant survive advantage at the point of 28-day, 90-day, 365-day and 1095-day after admission compared with cancer group (P < 0.001 for all) in the overall population (Fig. 3). Cancer patients had a similar length of ICU stay and slightly longer hospital stay (7.3-day VS 6.8-day, P < 0.001) compared with noncancer patients.
Subgroups analysis of short and medium-term survival of critically ill patients between with cancer and without cancer after PSM (Table 3)
Table 3
28-day and 90-day Survive in Patients With and Without Cancer by Admission Features after propensity score matching
Variable | 28-day survive, % (95% CI) | | 90-day survive, % (95% CI) |
Noncancer | Cancer | P Value | | Noncancer | Cancer | P Value |
Age | | | | | | | |
< 65 | 92.2(91.1–93.1) | 84.3(82.9–85.6) | < 0.001 | | 90.2(88.9–91.2) | 76.7(75.1–78.3) | < 0.001 |
≥ 65 | 80.9(79.7–82.0) | 81.1(79.9–82.2) | 0.697 | | 73.3(72.0-74.5) | 72.9(71.6–74.1) | 0.791 |
Gender | | | | | | | |
Female | 83.6(82.2–84.8) | 80.2(78.8–81.5) | 0.001 | | 78.2(76.8–79.6) | 72.3(70.8–73.8) | < 0.001 |
Male | 85.9(84.8–86.9) | 83.9(82.8–85.0) | 0.012 | | 80.0(78.8–81.2) | 75.9(74.5–77.1) | < 0.001 |
Ethnicity | | | | | | | |
Black | 90.2(87.4–92.5) | 80.4(76.7–83.6) | < 0.001 | | 84.0(80.6–86.9) | 69.9(65.7–73.7) | < 0.001 |
Asian | 85.2(79.3–89.4) | 80.6(74.6–85.4) | 0.215 | | 80.0(73.7–85.0) | 71.0(64.3–76.7) | 0.036 |
White | 84.9(83.9–85.8) | 83.7(82.7–84.6) | 0.111 | | 79.4(78.3–80.4) | 76.1(75.0-77.2) | < 0.001 |
Hispanic | 90.3(84.4–94.0) | 86.4(79.9–90.9) | 0.293 | | 87.7(81.3–92.0) | 74.7(67.0-80.8) | 0.005 |
Other | 80.2(77.4–82.8) | 73.9(70.8–76.7) | 0.002 | | 73.5(70.4–76.3) | 66.0(62.7–69.0) | 0.001 |
ICU type | | | | | | | |
SICU | 84.4(82.5–86.2) | 86.1(84.3–87.8) | 0.161 | | 78.6(76.5–80.6) | 78.6(76.4–80.6) | 0.843 |
MICU | 81.6(80.1–82.9) | 73.8(72.2–75.3) | < 0.001 | | 74.3(72.8–75.8) | 63.5(61.8–65.2) | < 0.001 |
CCU | 81.9(79.2–84.3) | 85.7(83.2–87.8) | 0.022 | | 77.4(74.5–80.0) | 78.5(75.7–81.0) | 0.409 |
CSRU | 95.5(94.1–96.5) | 94.4(92.9–95.5) | 0.218 | | 93.2(91.6–94.5) | 91.2(89.5–92.7) | 0.076 |
TSICU | 85.7(83.0-88.1) | 85.6(82.9–87.9) | 0.978 | | 80.3(77.2–83.0) | 77.3(74.2–80.1) | 0.216 |
Admission group | | | | | | | |
Elective | 96.8(95.7–97.5) | 96.5(95.5–97.4) | 0.774 | | 94.1(92.7–95.2) | 94.2(92.9–95.3) | 0.864 |
Emergency | 81.8(80.8–82.7) | 78.7(77.6–79.7) | < 0.001 | | 75.6(74.5–76.7) | 69.5(68.3–70.6) | < 0.001 |
Admission reasons | | | | | | | |
Cardiovascular | 86.2(85.0-87.3) | 83.4(82.1–84.6) | 0.003 | | 82.0(80.7–83.2) | 76.5(75.0-77.9) | < 0.001 |
Liver | 83.0(78.5–86.7) | 78.6(73.8–82.7) | 0.122 | | 75.8(70.8–80.0) | 62.2(56.7–67.2) | < 0.001 |
Mental | 81.1(78.2–83.7) | 77.7(74.6–80.5) | 0.090 | | 74.0(70.7–76.9) | 68.7(65.3–71.8) | 0.020 |
Renal | 76.6(73.8–79.1) | 78.3(75.5–80.7) | 0.374 | | 67.1(64.1–69.9) | 69.0(66.0-71.8) | 0.336 |
Respiratory | 87.4(85.4–89.1) | 84.4(82.3–86.3) | 0.003 | | 82.2(80.0-84.3) | 78.7(76.4–80.9) | 0.026 |
Coagulation | 87.7()83.9–90.7 | 78.9(74.2–82.9) | 0.001 | | 79.5(75.0–83.0) | 68.3(63.2–72.8) | 0.001 |
Other | 94.8(91.8–96.7) | 91.6(88.1–94.1) | 0.116 | | 92.3(88.9–94.8) | 81.7(77.2–85.4) | < 0.001 |
SOFA, | | | | | | | |
༜3 | 93.0(91.9–93.8) | 90.4(89.2–91.3) | 0.001 | | 89.6(88.4–90.7) | 82.4(81.0-83.8) | 0.003 |
≥3 | 80.1(78.9–81.2) | 77.4(76.2–78.6) | 0.002 | | 73.1(71.8–74.4) | 69.5(68.1–70.8) | < 0.001 |
SAPS II | | | | | | | |
༜24 | 98.1(97.1–98.7) | 96.7(95.4–97.7) | 0.044 | | 97.3(96.2–98.1) | 93.2(91.5–94.6) | < 0.001 |
≥ 24 | 82.4(81.5–83.4) | 80.1(79.1–81.1) | 0.001 | | 75.9(74.8–76.9) | 71.5(70.4–72.6) | < 0.001 |
APS III | | | | | | | |
༜38 | 94.5(93.6–95.2) | 92.8(91.9–93.6) | 0.005 | | 91.6(90.6–92.5) | 86.5(85.3–87.6) | < 0.001 |
≥38 | 77.1(75.8–78.3) | 73.6(72.3–75.0) | 0.001 | | 69.2(67.8–79.6) | 64.3(62.8–65.7) | < 0.001 |
LODS | | | | | | | |
༜3 | 93.9(92.8–94.7) | 90.9(89.8–92.0) | < 0.001 | | 90.8(89.6–91.8) | 83.5(82.0-84.8) | < 0.001 |
≥3 | 80.2(79.0-81.3) | 77.8(76.6–78.9) | 0.006 | | 73.2(72.0-74.5) | 69.6(68.3–70.8) | < 0.001 |
OASIS | | | | | | | |
༜30 | 95.6(94.8–96.3) | 92.9(91.9–93.7) | < 0.001 | | 92.0(91.0-92.9) | 86.0(84.8–87.1) | < 0.001 |
≥30 | 76.4(75.1–77.6) | 73.7(72.3–75.0) | 0.007 | | 69.1(67.7–70.5) | 64.8(63.3–66.2) | < 0.001 |
Elixhause comorbidity | | | | | | | |
༜4 | 92.6(91.6–93.6) | 91.7(90.5–92.7) | 0.232 | | 90.8(89.7–91.9) | 86.7(85.3–88.0) | < 0.001 |
≥4 | 80.8(79.7–81.9) | 77.6(76.4–78.7) | < 0.001 | | 73.2(71.9–74.4) | 68.1(66.7–69.3) | < 0.001 |
RRT | | | | | | | |
Yes | 69.5(61.3–76.3) | 71.0(62.9–77.7) | 0.951 | | 61.7(53.5–68.8) | 63.5(55.1–70.7) | 0.930 |
No | 85.2(84.3–86.0) | 82.5(81.6–83.4) | < 0.001 | | 79.0(78.7–80.5) | 74.5(73.5–75.5) | < 0.001 |
MV | | | | | | | |
Yes | 81.1(79.7–82.5) | 78.5(77.0-79.1) | 0.011 | | 76.3(74.8–77.8) | 72.2(70.5–73.7) | < 0.001 |
No | 87.4(86.1–88.4) | 84.8(83.9–86.0) | 0.001 | | 81.2(80.0-82.3) | 75.8(74.5–77.1) | < 0.001 |
Vasopressor | | | | | | | |
Yes | 79.1(77.3–80.8) | 77.5(75.7–79.2) | 0.254 | | 74.0(72.0-75.8) | 72.3(70.3–74.2) | 0.249 |
No | 87.1(86.2–88.0) | 84,1(83.1–85.1) | < 0.001 | | 81.3(80.2–82.3) | 75.1(73.9–76.2) | < 0.001 |
Sepsis | | | | | | | |
Yes | 64.0(60.0-67.7) | 51.3(47.2–55.3) | < 0.001 | | 52.4(48.3–56.3) | 41.7(37.7–45.7) | < 0.001 |
No | 86.7(85.9–87.5) | 84.9(84.0-85.7) | 0.005 | | 81.6(80.6–82.5) | 77.1(76.1–78.1) | < 0.001 |
Infection | | | | | | | |
Yes | 78.9(77.5–80.3) | 75.2(73.6–76.6) | < 0.001 | | 70.0(68.3–71.5) | 64.8(63.1–66.4) | < 0.001 |
No | 89.2(88.2–90.1) | 87.6(88.6) | 0.027 | | 86.0(84.9–87.0) | 81.4(80.2–82.6) | < 0.001 |
Abbreviations: Sequential Organ Failure Assessment, SOFA; Simplified Acute Physiology Score II, SAPSII; Logistic Organ Dysfunction Score, LODS; Oxford Acute Severity of Illness Score, OASIS; Acute Physiology Score, APSIII; Surgical intensive care unit, SICU; Medical intensive care unit, MICU; Coronary care unit, CCU; Cardiac surgery recovery unit, CSRU; Traumatic surgical intensive care unit, TSICU; mechanical ventilation, MV; renal replacement therapy, RRT. |
The noncancer patients had survive advantage than cancer patients in MICU (P < 0.001, Supp. Figure 1). However, when patients admitted by SICU, the survive advantage disappeared at the point of 28-day and 90-day (P > 0.05 for both, Supp. Figure 2). Table 3 shows 28-day and 90-day survive in patients with and without cancer stratified according to distinct patient subgroups. Compared with noncancer group, 28-day and 90-day survive rate was lower in the cancer group when patient’s age < 65, black, in MICU, emergency admission (Supp. Figure 3), admission because of cardiovascular or respiratory or coagulation dysfunction, Elixhauser comorbidity index score ≥ 4, and patients without RRT or vasopressor support (P < 0.05 for all). 28-day and 90-day survive rate showed no difference between cancer and noncancer group when patients’ age ≥ 65, patients in SICU or CSRU or TSICU, elective admission (Supp. Figure 4), patients with RRT or vasopressor support (P > 0.05 for all). Although when patients were Asian or White or Hispanic, admission because of liver or mental or renal disorder, Elixhauser comorbidity index score < 4, patients with cancer showed no different 28-day survive compared with noncancer patients (P > 0.05 for all), the survive advantage appeared at 90-day survive for noncancer patients(P < 0.05 for all). However, for patients in CCU, cancer group has higher 28-day survive rate than the noncancer group (P = 0.022) and the survive advantage disappeared at the point of 90-day (P = 0.409).