Effectiveness of Laxatives in the Elderly - NIHR Health Technology ...

Effective laxative treatments
for constipation
Significant improvements in bowel movement
frequency have been observed with a stimulant
laxative containing cascara and, also, with an
osmotic laxative. Non-significant effects of
laxatives on frequency have been reported in
four other placebo-controlled RCTs. Since the
largest of these trials had only 51 participants,
the trials may simply have lacked the statistical
power to detect an effect. Information on other
outcomes, such as improvements in symptoms
and stool consistency, are not reported for all
trials. However, improvements in both stool
consistency and symptoms have been reported
in placebo-controlled trials of psyllium, lactulose
and lactitol treatment.
There is a commonly held clinical impression
that fibre is less effective than other types of
laxative in improving bowel movement frequency.
However, to examine this question in detail, direct
comparisons between fibre and other laxative
classes and types within the same trial would be
required. Very few of such direct comparisons
appear to have been carried out in controlled trials.
Eight trials compared laxative agents, and the two
higher quality trials suggested that Agiolax may be
more effective than lactulose.
These findings are in accord with the systematic
review of the treatment of constipation in adults
by Tramonte and colleagues (1997), in which it
was concluded that laxatives and fibre consistently
increased bowel movement frequency compared
with placebo, with the increase being of the order
of 1.5 bowel movements per week. Direct comparisons
were found to be inconclusive because of the
small number of studies found and methodological
flaws. There was no direct evidence that fibre was
more or less effective than any other laxative
in adults.
The results of the trials in elderly people
can also be summarised separately for two
specific groups.
Chapter 5
Summary and
research recommendations
Health Technology Assessment 1997; Vol. 1: No. 13
• Ambulant elderly people
The majority of trials have been conducted
among a limited sample of elderly people.
Most participants were recruited either in
nursing homes or in hospitals, and only two
trials included elderly patients treated as
out-patients. In one of these, in which the
bulk laxative psyllium was compared with
placebo, a larger weekly increase in bowel
movement frequency was found than in any
other placebo-controlled trial, although the
numbers of participants in the trial were
small and the difference was not statistically
significant. The other trial among elderly
out-patients compared two bulk laxatives,
psyllium and calcium polycarbophil. Psyllium
was more effective in improving bowel movement
frequency and stool consistency, although
the latter was a non-significant trend. These
results suggest that fibre may be effective
in the ambulant elderly.
• Elderly people in hospitals and
nursing homes
The trials in hospital and nursing-home
patients suggest that stimulant and osmotic
laxatives may be more effective in these
patients than bulk agents in increasing bowel
movement frequency. However, this result
is based on a few studies and the results
regarding improvement in symptoms and
stool consistency are inconclusive.
The major criticism of the trials identified in
this area is that they lack power and are, therefore,
unlikely to detect effects of treatment. They are
certainly too small to adequately assess effects
of treatment on uncommon outcomes, such as
impaction, and adverse effects.
A further potential problem lies in the assumption
that the patients in the trials are a homogeneous
group. There are many causes of constipation,
some of which may be of particular relevance to
the nursing home or hospital populations which
feature in most of the trials, such as dietary,
psychiatric and environmental causes (Moriarty
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