A validated algorithm to identify recurrence of bladder cancer: a register-based study in Denmark

Figures & data

Figure 1 Schematic overview of the algorithm.

Notes: ^aCystectomy or >15 fractions of radiotherapy. ^bNinety days after cystectomy and 180 days after the last fraction of radiotherapy.

Figure 2 Flowchart of study population.

Abbreviations: BC, bladder cancer; DaBlaCa-data, Danish Bladder Cancer Database.

Table 1 Characteristics of included patients stratified on cancer recurrence status in the DaBlaCa-data (n=187)

	Cancer recurrence n (%)a	No cancer recurrence n (%)a
N	128 (68)	59 (32)
Sex
Female	36 (28)	15 (25)
Male	92 (72)	44 (75)
Age, median (IQR)	68 (62–74)	73 (67–81)
Primary cancer treatment regime
Cystectomy	105 (82)	26 (44)
Radiotherapy	23 (18)	33 (56)
Tumor stage primary cancer
Local	88 (69)	53 (90)
Regional	9 (7)	<5 (×)b
Missing	31 (24)	<5 (×)b
Comorbidity at primary cancer
CCI: 0	71 (56)	21 (36)
CCI: 1–2	39 (31)	28 (48)
CCI: 3+	18 (14)	10 (17)

Notes:

a Numbers are n (%) if nothing else is stated.

b Data are masked for data privacy for less than five observations.

Abbreviations: CCI, Charlson’s comorbidity index; DaBlaCa-data, Danish Bladder Cancer Database; IQR, interquartile range.

Table 2 Concordance of bladder cancer recurrence identified by the gold standard and the algorithm

Recurrence by algorithm	Recurrence by gold standard
	Yes	No	Total
Yes	109	6	115
No	19	53	72
Total	128	59	187

Table 3 Performance of the algorithm for bladder cancer recurrencea

Algorithm performance	%(95% CI)
Sensitivity	85.2 (77.8–90.8)
Specificity	89.8 (79.2–96.2)
Positive predictive value	94.8 (89.0–98.1)
Negative predictive value	73.6 (61.9–83.3)
Kappa agreement	86.6 (80.1–91.1)
Kappa (95% CI)	0.71 (0.60–0.70)

Note:

a Numbers are percentages (95% CI) if nothing else is stated.

Abbreviation: CI, confidence interval

Figure S1 Discordance between gold standard and algorithm on recurrence date.

Table S1 Agreement between the date of recurrence of bladder cancer identified by the algorithm and the gold standard

Interval of concordance	% (95% CI)
Same date	18 (12–27)
≤7 days	33 (25–43)
≤30 days	64 (54–73)
≤60 days	84 (77–91)
≤90 days	90 (84–95)
>90 days	9 (4–15)

Abbreviation: CI, confidence interval.