Economic impact of low dose polyethylene glycol 3350 plus electrolytes compared with lactulose in the management of idiopathic constipation in the UK.
OBJECTIVE
To estimate the economic impact of using low dose polyethyene glycol 3350 (PEG 3350) plus electrolytes (PEG+E) compared with lactulose in the treatment of idiopathic constipation in ambulant patients. DESIGN AND PERSPECTIVE: This was a decision analytic modelling study performed from the perspective of the UK's National Health Service (NHS).


METHODS
The clinical outcomes from a previously reported single-blind, randomised, multicentre trial were used as the clinical basis for the analysis. These data were combined with resource utilisation estimates derived from a panel of six general practitioners (GPs) and four nurses enabling a decision model to be constructed depicting the management of idiopathic constipation with either PEG+E or lactulose over 3 months. The model was used to estimate the expected 3-monthly NHS cost of using either laxative to manage idiopathic constipation.


RESULTS
The expected 3-monthly NHS cost of using PEG+E or lactulose to manage idiopathic constipation was estimated to be 85 pound sterling and 96 pound sterling per patient, respectively (1999/2000 values). However, significantly more patients were successfully treated with PEG+E than lactulose (53% versus 24%; p < 0.001) at 3 months. GP visits were the primary cost driver for both PEG+E- and lactulose-treated patients, accounting for 56% (2.9 visits) and 73% (4.4 visits), respectively, of the expected NHS cost per patient at 3 months. Among PEG+E-treated patients, the acquisition cost of PEG+E was the secondary cost driver, accounting for 30% of the expected NHS cost per patient at 3 months, whereas the acquisition cost of lactulose accounted for only 11% of the expected NHS cost per lactulose-treated patient. District nurse domiciliary visits accounted for 4% and thyroid function tests for 2%. The costs of switched laxatives, concomitant laxatives, and gastroenterologist and colorectal surgeon visits collectively accounted for up to 9% of the total.


CONCLUSIONS
The true cost of managing idiopathic constipation is impacted on by a broad range of resources and not only laxative acquisition costs. This study indicated that managing idiopathic constipation with PEG+E instead of lactulose reduces the expected 3-monthly NHS cost by 11 pound sterling per patient. Moreover, using PEG+E instead of lactulose is expected to double the percentage of patients successfully treated at 3 months. Hence, PEG+E is a dominant treatment compared with lactulose. This suggests that the decision to use either PEG+E or lactulose to treat idiopathic constipation should be based on efficacy, safety, patient preferences and total management costs, and not drug acquisition costs.
Christie
Angela H
AH
Catalyst Health Economics Consultants, Northwood, Middlesex, United Kingdom.
Culbert
Pearl
P
Guest
Julian F
JF
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002908:Chronic Disease; D003248:Constipation / Q000188:drug therapy*; D003362:Cost-Benefit Analysis; D003661:Decision Support Techniques; D004334:Drug Administration Schedule; D004359:Drug Therapy, Combination; D017850:Economics, Pharmaceutical; D004573:Electrolytes / Q000008:administration & dosage* / Q000191:economics* / Q000378:metabolism; D005765:Gastrointestinal Agents / Q000008:administration & dosage* / Q000191:economics* / Q000378:metabolism; D006801:Humans; D007792:Lactulose / Q000008:administration & dosage* / Q000191:economics* / Q000378:metabolism; D008875:Middle Aged; D011092:Polyethylene Glycols / Q000008:administration & dosage* / Q000191:economics* / Q000378:metabolism; D016896:Treatment Outcome; D006113:United Kingdom
D004573:Electrolytes; D005765:Gastrointestinal Agents; D011092:Polyethylene Glycols; D007792:Lactulose