Table 2 Base case inputs by population (data value or type; source)

Clinical parameters

 Mean age (years)

70; ART (with SIADH)^a

64; ART (SCLC with SIADH)^a

69; ART (pneumonia with SIADH)^a

 % Male

33 %; ART (with SIADH)^a

31 %; ART (SCLC with SIADH)^a

43 %; ART (pneumonia with SIADH)^a

 Baseline [Na⁺]

125; HN Registry^b

123; HN Registry [38]

125; HN Registry^b

 Baseline probability [Na⁺] correction (≥135 mmol/L)

Binary logistic regression; HN Registry (SIADH)^b

Binary logistic regression; HN Registry (SIADH)^b

Binary logistic regression; HN Registry (SIADH)^b

 Odds ratio normalisation tolvaptan vs. NAT

11.50; SALT I & II [4]

11.50; SALT I & II [4]

11.50; SALT I & II [4]

 Duration of tolvaptan treatment

Mean 3 days; Lognormal survival distribution; HN Registry (SIADH)^b

Mean 4 days; Petereit et al. [28]

Mean 3 days; clinical opinion

 Early tolvaptan treatment discontinuation rule

2 days

2 days

2 days

 Mean hospital LOS NAT

8.00; SALT I & II (SIADH with [Na⁺] <130 mmol/L) [4]

8.00; SALT I & II (SIADH with [Na⁺] <130 mmol/L) [4]

8.00; SALT I & II (SIADH with [Na⁺] <130 mmol/L) [4]

 Percentage reduction hospital LOS with tolvaptan

20.0 %; SALT I & II (SIADH with [Na⁺] <130 mmol/L)^c

20.0 %; SALT I & II (SIADH with [Na⁺] <130 mmol/L)^c

20.0 %; SALT I & II (SIADH with [Na⁺] <130 mmol/L)^c

 Probability inpatient mortality

2.2 %; ART (with SIADH)^a

4.4 %; ART (SCLC with SIADH)^a

6.2 %; ART (pneumonia with SIADH)^a

 Long-term survival

Based on age; Swedish life-tables [24]

Based on disease; Gompertz distribution from ART (SCLC with SIADH)

Based on age; Swedish life-tables [24]

 Time to readmission

Weibull distribution; ART (with SIADH)^a

Weibull distribution; ART (SCLC with SIADH)^a

Weibull distribution; ART (pneumonia with SIADH)^a

 Probability of SIADH (and HN) resolution at end of inpatient admission

100 %; assumption

88 %; List et al. [39]

100 %; assumption

 Time to resolution^d

NA in base case

NA in base case

NA in base case

Costs

 Tolvaptan dosing/cost assumption

15/30 mg once daily^e

15/30 mg once daily^e

15/30 mg once daily^e

 Care setting for admission

Internal medicine clinic

Oncology clinic

Pulmonary care clinic

 Discharge location

Home

Home

Home

 Palliative care costs

None

Applied for a maximum of 84 days (3 months)

None

 Chemotherapy costs

None

Applied once per inpatient stay

None

 Percentage patients in work between readmissions

17 %; [40]

0 %; Assumption

17 %; [40]

HRQL

 Baseline utility

0.58; SALT I & II [41]

0.61; Loveman et al. [20] with HN reduction from SALT I & II [41]

0.73; Schuetz et al. [21] with HN reduction from SALT I & II [41]

 Treatment-specific change in EQ-5D at Day 4

Absolute change in simulated EQ-5D at Day 30 from SALT I & II [41]

Absolute change in simulated EQ-5D at Day 30 from SALT I & II [41]

Absolute change in simulated EQ-5D at Day 30 from SALT I & II [41]

Model structure

 Time horizon

30 days

180 days

30 days