Serum and urine concentrations of morphine and morphine metabolites in patients with advanced cancer receiving continuous intravenous morphine: an observational study

Table 5 Linear regression model of factors predictive of serum and urine concentrations of morphine (n = 24)

Outcome	Factors Contributing to outcome	Estimates for individual factors with model 1		Estimate for model 1	Estimate for model 2
Outcome	Factors Contributing to outcome	Coef.	P-value	Adjusted R²	Adjusted R²
Serum
M (Day 1)	Morphine dose (mg/24 h)	0.60	0.01	0.33	0.08
Urine
M (Day 1)	Morphine dose (mg/24 h)	0.52	0.61	0.10	0.14
	Age	−2.05	0.06
	Gender	−2.02	0.06
M (Day 2)	Morphine dose (mg/24 h)	0.97	0.00	0.40	−0.05
	Creatinine	−0.44	0.07
	Gender	−0.48	0.03
M (Day3)	Morphine dose (mg/24 h)	0.58	0.01	0.56	0.29

Estimated Model 1: Independent factors in all analyses were morphine dose, gender, daily intravenous fluid amounts, creatinine, ALT, and age
Estimated Model 2: Independent factors in all analyses were gender, daily intravenous fluid amounts, creatinine, ALT, and age (Morphine dose was omitted from Model 1)
As for Urine model, daily urine output was used instead of daily intravenous fluid amounts in each model
Coef standardized coefficient in regression model, M Morphine concentration (nmol/liter), ALT alanine transaminase

ISSN: 1472-684X