Predictive factors for prolonged sick leave in breast cancer patients treated with adjuvant therapies: a retrospective registry study

Figures & data

Table 1. Characteristics of study participants.

Characteristics	No sick leave (n, 147)	Expected sick leave (n, 845)	Prolonged sick leave (n, 341)	Total (n, 1333)
Demographic characteristics
Age, years	54.6 (7.4)	52.2 (7.5)	51.5 (7.9)	52.3 (7.7)
Municipality of residence, n (%)
Espoo	39 (26.5)	164 (19.4)	58 (17.0)	261 (19.6)
Helsinki	51 (34.7)	337 (39.9)	118 (34.6)	506 (38.0)
Vantaa	18 (12.2)	99 (11.7)	54 (15.8)	171 (12.8)
Other	39 (26.5)	245 (29.0)	111 (32.6)	395 (29.6)
Income, 10 000 €/year	–	39 (24)	31 (19)	37 (23)
Disease characteristics
Histological classification^a, n (%)
Ductal	129 (87.8)	708 (83.8)	288 (84.5)	1125 (84.4)
Lobular	14 (9.5)	134 (15.9)	43 (12.6)	191 (14.3)
Other	8 (5.4)	43 (5.1)	23 (6.7)	74 (5.6)
Receptor expression status, n (%)
Oestrogen receptor
Positive	134 (91.2)	754 (89.2)	276 (80.9)	1164 (87.3)
Negative^b	anon.	anon.	anon.	160 (12.0)
Unknown^b	anon.	anon.	anon.	9 (0.7)
Progesterone receptor
Positive	110 (74.8)	631 (74.7)	219 (64.2)	960 (72.0)
Negative^b	anon.	anon.	anon.	363 (27.2)
Unknown^b	anon.	anon.	anon.	10 (0.8)
HER2
Positive	14 (9.5)	84 (9.9)	35 (10.3)	133 (10.0)
Negative^b	anon.	anon.	anon.	1190 (89.3)
Unknown^b	anon.	anon.	anon.	10 (0.8)
Triple negative (ER-PR-HER2-)	10 (6.8)	64 (7.6)	54 (15.8)	128 (9.6)
Treatment characteristics
Active treatment
Episodes per patient	1.1 (0.3)	1.1 (0.3)	1.1 (0.4)	1.1 (0.3)
Duration, months	4.2 (3.3)	5.1 (3.7)	5.4 (2.7)	5.1 (3.4)
Adjuvant treatment line, n (%)
Radiotherapy	87 (59.2)	378 (44.7)	61 (17.9)	526 (39.5)
Chemotherapy + radiotherapy^b	anon.	anon.	anon.	715 (53.6)
Chemotherapy^b	anon.	anon.	anon.	92 (6.9)
Surgical treatment, n (%)
Mastectomy	28 (19.0)	191 (22.6)	135 (39.6)	354 (26.6)
BCS	128 (87.1)	690 (81.7)	231 (67.7)	1049 (78.7)
Reconstruction, n (%)	5 (3.4)	84 (9.9)	62 (18.2)	151 (11.3)
Axillary evacuation, n (%)	39 (26.5)	242 (28.6)	144 (42.2)	425 (31.9)
Endocrine treatment, n (%)	107 (72.8)	650 (76.9)	260 (76.2)	1017 (76.3)
Other medications, n (%)
Pain killers	13 (8.8)	59 (7.0)	44 (12.9)	116 (8.7)
Antiemetics	51 (34.7)	438 (51.8)	258 (75.7)	747 (56.0)
HCRU characteristics
Outpatient visits/contacts^c
Total number per patient	6.8 (5.8)	7.8 (5.9)	10.1 (7.6)	8.2 (6.4)
Per month of active treatment (n/month)	1.7 (0.9)	1.6 (0.9)	1.9 (1.3)	1.7 (1.0)
ED visits
Total number per patient	0.2 (0.6)	0.4 (0.9)	0.6 (1.0)	0.4 (0.9)
Per month of active treatment (n/month)	0.0 (0.1)	0.1 (0.1)	0.1 (0.2)	0.1 (0.2)
Inpatient stays
Total number per patient	0.2 (0.5)	0.3 (0.5)	0.3 (0.6)	0.3 (0.6)
Days	0.5 (1.9)	0.6 (1.9)	1.1 (4.5)	0.7 (2.8)

Data are shown as mean (standard deviation) for continuous variables and number (% of the total number of the group [first three columns] or % of the total [last column] for categorical variables.

^aHistological classification was derived from the ICD-10 classification, C50.X1 ductal; C50.X2 lobular; C50.X0, C50.X9 and D01.5 other. Both ductal and lobular carcinoma were diagnosed in 57 (4.3%) of patients.

^bTo protect study participants’ anonymity, the frequency present in the results is five at minimum.

^cVisits/contacts outside active treatment i.e., outpatient visits on days of active treatment are excluded.

Table 2. Sick leaves of the patients before, during, and after active breast cancer treatment.

Time frame	No sick leave (n, 147)		Expected sick leave (n, 845)		Prolonged sick leave (n, 341)		Total (n, 1 333)
	Mean (SD)	Median (IQR)	Mean (SD)	Median (IQR)	Mean (SD)	Median (IQR)	Mean (SD)	Median (IQR)
During treatment	–	–	15.6 (10.9)	16.6 (21.3)	27.1 (5.9)	28.6 (2.0)	16.8 (11.9)	21.5 (24.7)
After treatment
+ M1	–	–	4.3 (7.6)	0.0 (5.0)	29.3 (3.0)	30.0 (0.0)	10.2 (12.9)	0.0 (28.0)
+ M2	–	–	0.2 (1.8)	0.0 (0.0)	24.1 (9.6)	30.0 (12.0)	6.3 (11.6)	0.0 (3.0)
+ M3	–	–	0.3 (2.5)	0.0 (0.0)	18.4 (13.9)	30.0 (30.0)	4.9 (10.8)	0.0 (0.0)
+ M4	–	–	0.6 (3.8)	0.0 (0.0)	15.3 (14.4)	19.0 (30.0)	4.3 (10.2)	0.0 (0.0)
+ M5	–	–	0.7 (4.1)	0.0 (0.0)	12.8 (14.2)	0.0 (30.0)	3.7 (9.5)	0.0 (0.0)
+ M6	–	–	0.7 (4.0)	0.0 (0.0)	10.4 (13.8)	0.0 (30.0)	3.1 (8.8)	0.0 (0.0)
+ M7	–	–	0.6 (3.7)	0.0 (0.0)	8.5 (13.0)	0.0 (25.0)	2.5 (8.0)	0.0 (0.0)
+ M8	–	–	0.6 (3.8)	0.0 (0.0)	7.3 (12.3)	0.0 (12.0)	2.2 (7.5)	0.0 (0.0)
+ M9	–	–	0.5 (3.7)	0.0 (0.0)	6.8 (12.3)	0.0 (0.0)	2.1 (7.4)	0.0 (0.0)
+ M10	–	–	0.5 (3.5)	0.0 (0.0)	6.2 (11.7)	0.0 (0.0)	1.9 (7.0)	0.0 (0.0)
+ M11	–	–	0.6 (3.8)	0.0 (0.0)	6.1 (11.7)	0.0 (0.0)	1.9 (7.1)	0.0 (0.0)
+ M12	–	–	0.7 (4.1)	0.0 (0.0)	5.9 (11.7)	0.0 (0.0)	1.9 (7.1)	0.0 (0.0)

Diagnosis time was defined as the first healthcare contact with ICD-10 diagnosis code starting with C50 or D01.5. The start and end of active treatment were defined as the first and last day of active treatment (surgery, chemotherapy or radiotherapy), respectively.

Sick leave days per month before diagnosis, from diagnosis to start of the treatment, and during treatment were calculated by summing up the sick leave days accumulated during each period (in days) and dividing by the total duration of the period (in months).

Table 3. Univariate and multivariate logistic regression analysis for prolonged sick leave after active breast cancer treatment.

	Univariate analysis		Multivariate analysis
			Model 1		Model 2
Variable	OR (95% CI)	p-Value	OR (95% CI)	p-Value	OR (95% CI)	p-Value
Demographic characteristics
Age, years	0.97 (0.96–0.99)	<.001
Municipality of residence
Espoo	1 (ref)		1 (ref)
Helsinki	0.97 (0.67–1.41)	.858	0.92 (0.59–1.45)	.070
Other	1.24 (0.85–1.83)	.262	1.36 (0.87–2.15)	.020
Vantaa	1.76 (1.13–2.75)	.012	1.71 (1.01–2.91)	.046
Income, 10 000 €/year	0.98 (0.98–0.99)	<.001			0.98 (0.97–0.99)	<.001
Disease characteristics
Histological classification
Ductal	1.65 (1.21–2.27)	.002
Lobular	0.91 (0.60–1.34)	.636
Receptor expression status
ER+	0.49 (0.35–0.70)	<.001
PR+	0.62 (0.47–0.81)	.001
HER2+	1.10 (0.71–1.65)	.667
Triple negative (ER-PR-HER2-)	2.35 (1.59–3.43)	<.001			1.65 (1.03–2.65)	.037
Treatment characteristics
Active treatment
Episodes	1.32 (0.86–1.99)	.187
Duration, months	1.06 (1.03–1.10)	.001
Adjuvant treatment line
Radiotherapy	1 (ref)		1 (ref)		1 (ref)
Chemotherapy	10.56 (6.32–17.80)	<.001	11.60 (6.25–21.7)	<.001	9.76 (5.07–19.1)	<.001
Chemotherapy + radiotherapy	4.96 (3.51–7.14)	<.001	5.90 (3.88–9.26)	<.001	5.67 (3.69–8.98)	<.001
Mastectomy	2.54 (1.93–3.33)	<.001
BCS	0.42 (0.31–0.56)	<.001
Reconstruction	2.66 (1.86–3.79)	<.001	1.68 (1.08–2.57)	.019	1.54 (0.98–2.41)	.060
Axillary evacuation	1.90 (1.46–2.47)	<.001
Endocrine treatment	1.03 (0.77–1.41)	.835
Symptom medications
Pain killers	1.62 (1.06–2.43)	.024
Antiemetics	4.39 (3.24–6.04)	<.001
HCRU characteristics
Outpatient visits/contacts^a
Total number	1.07 (1.05–1.09)	<.001
Per month of active treatment (n/month)	1.20 (1.07–1.35)	.002	1.44 (1.24–1.69)	<.001	1.57 (1.34–1.86)	<.001
ED visits
Total number	1.24 (1.09–1.41)	.001
Per month of active treatment (n/month)	3.83 (1.90–7.79)	<.001
Inpatient stays
Number	1.32 (1.06–1.63)	.013
Days	1.05 (1.01–1.10)	.030

Model 1 included all patients (n, 1333) and Model 2 only patients with at least one reported sick leave or disability pension during 2016–2018. All the significant predictors from univariate analysis were entered to multivariate analysis with backward selection except for yearly income, which was entered in Model 2 but not in Model 1. Prior to analysis, data were divided into training (80%) and test data sets (20%). The VIF values of all the variables in multivariate models were less than 2.0. AUROC of Model 1 (for test data set) was 0.764 (95% CI 0.699–0.829) and of AUROC of Model 2 (for test data set) 0.740 (95% CI 0.670–0.812).

^aVisits/contacts outside active treatment i.e., outpatient visits on days of active treatment are excluded.

Data availability statement

The data that support the findings of this study are available on request from the corresponding author PPS. The data are not publicly available due to restrictions e.g., their containing information that could compromise the privacy of research participants.