Hospital use among patients with lung cancer complicated by bone metastases and skeletal- related events: a population-based cohort study in Denmark

Figures & data

Figure 1 Observation periods for patients with one SRE and patients with multiple SREs.

Abbreviation: SRE, skeletal-related event.

Table 1 Descriptive characteristics of 1,147 lung cancer patients with bone metastases and at least one subsequent SRE

Characteristics
Age at primary cancer diagnosis in yearsa Sex distribution, n (%)	65.0 (58.5–72.5)
Male	661 (57.6)
Female	486 (42.4)
Tumor stage at primary cancer diagnosis, n (%)
Localized	62 (5.4)
Regional	124 (10.8)
Metastatic	930 (81.1)
Missing	31 (2.7)
SRE, n (%)
Single SRE	282 (24.6)
Conventional external radiation therapy (CERT)	214 (18.7)
Pathological fracture (PF)/osteoporotic fracture (OF)	17 (1.5)
Spinal cord compression (SCC)	41 (3.6)
Surgery to bone (SB)	10 (0.9)
Multiple SREs	865 (75.4)
Multiple treatments with CERTs only	603 (52.6)
CERT combined with PF/OF, SCC and/or SB	227 (19.8)
PF, SCC and/or SB	35 (3.1)
Months from primary cancer diagnosis to bone metastasesa	0.9 (0.1–3.3)
Months from bone metastases to first SREa	0.4 (0.1–1.3)
Months from first SRE to end of follow-upa	2.3 (0.9–3.1)

Note:

a Data presented as median (interquartile range).

Abbreviations: CERT, conventional external radiation therapy; n, number; SRE, skeletal-related event.

Table 2 Hospital use and follow-up time

	1 SRE (n=282)			>1 SRE (n=865)
	Pre-SRE	Diagnostic period	Post-SRE	Pre-SRE	Diagnostic period	Post-SRE
Inpatient hospital admission
Patients, n (%)	203 (72.0)	171 (60.6)	239 (84.8)	596 (68.9)	557 (64.4)	768 (88.8)
Visits, n	421	195	413	1,141	642	1,703
Median (IQR)	1 (0–2)	1 (0–1)	1 (1–2)	1 (0–2)	1 (0–1)	1 (1–2)
Per 100 person-days (CI)	1.7 (1.5–1.8)	4.6 (4.0–5.3)	2.9 (2.6–3.2)	1.5 (1.4–1.6)	4.9 (4.6–5.3)	2.7 (2.6–2.8)
Rate ratio (CI)a	1 (reference)	2.8 (2.3–3.3)	1.7 (1.5–2.0)	1 (reference)	3.4 (3.1–3.7)	1.8 (1.7–2.0)
Inpatient bed-days
Patients, n (%)	203 (72.0)	171 (60.6)	239 (84.8)	596 (68.9)	557 (64.4)	768 (88.8)
Days, n	3,448	1,411	3,538	8,308	4,561	17,914
Median (IQR)	7.5 (0–18)	2 (0–9)	10 (3–18)	4 (0–14)	3 (0–10)	16 (7–28)
Per 100 person-days (CI)	13.6 (13.1–14.0)	33.4 (31.7–35.1)	24.7 (23.9–25.6)	10.7 (10.4–10.9)	35.2 (34.1–36.2)	28.2 (27.8–28.6)
Rate ratio (CI)a	1 (reference)	2.5 (2.3–2.6)	1.8 (1.7–1.9)	1 (reference)	3.3 (3.2–3.4)	2.6 (2.6–2.7)
Emergency room visits
Patients, n (%)	41 (14.5)	23 (8.2)	18 (6.4)	124 (14.3)	56 (6.5)	164 (19.0)
Visits, n	54	24	20	141	59	189
Median (IQR)	0 (0–0)	0 (0–0)	0 (0–0)	0 (0–0)	0 (0–0)	0 (0–0)
Per 100 person-days (CI)	0.2 (0.2–0.3)	0.6 (0.4–0.8)	0.1 (0.1–0.2)	0.2(0.2–0.2)	0.5 (0.4–0.6)	0.3 (0.3–0.3)
Rate ratio (CI)a	1 (reference)	2.7 (1.6–4.3)	0.7 (0.4–1.1)	1 (reference)	2.5 (1.9–3.4)	1.6 (1.3–2.0)
Outpatient clinic visits
Patients, n (%)	250 (88.7)	195 (69.1)	248 (87.9)	735 (85.0)	627 (72.5)	810 (93.6)
Visits, n	1,467	396	1,075	3,961	1,228	7,205
Median (IQR)	4 (2–7)	1 (0–2)	2 (1–5)	3 (1–7)	1 (0–2)	7 (4-11)
Per 100 person-days (CI)	5.8 (5.5–6.1)	9.3 (8.5–10.3)	7.5 (7.1–8.0)	5.1 (4.9–5.2)	9.5 (8.9–10.0)	11.3 (11.1–11.6)
Rate ratio (CI)a	1 (reference)	1.6 (1.4–1.8)	1.3 (1.2–1.4)	1 (reference)	1.9 (1.7–2.0)	2.2 (2.1–2.3)
Person-time, days	25,380	4,230	14,298	77,850	12,975	63,586

Note:

a The number of visits/days per person-day with the pre-diagnostic period as reference.

Abbreviations: CI, confidence interval; IQR, interquartile range; SRE, skeletal-related event.