Systematic review of constipation therapy
17 Sep, 08 | by Ian Wacogne
In this systematic review of constipation therapy the authors can find no evidence that laxative is better than placebo, although PEG was associated with higher treatment success than other laxatives. Here.
Well, here’s one right out of the “I didn’t see that coming” box. And as far as their conclusions are concerned, they are, for me, completely contra intuitive. I know that Bob Phillips will comment here, but here’s a few guesses from me on this.
1. There’s the parachute effect. There aren’t any RCTs on parachute efficacy compared to placebo in stopping you hit the ground. It’s too darn obvious.
2. There’s the heterogeneity of the outcomes, which seems to affect the way in which these authors can conflate their results. So, one study looks at soiling, another at stool frequency, another at other symptoms of constipation.
Well, that will do for now. I can tell you this: I will still be using laxatives for the child I see in clinic tomorrow with constipation. But whether this means that I’m just being an old-fashioned idiot, or whether my treatment success is illusory, or whichever it is, I’m not sure.
Incidentally, there is a NICE review on this underway; hopefully their conclusions will be a little less nihilistic…
Go on then - I’ll bite.
Should there be trials of laxative vs placebo? You know, there might be a good argument for it. What proportion of chronic pain is cured by a placebo TENS machine? And a real TENS machine? (It’s about 40%.)((For both)) How much placebo effect could we expect? (Placebos work in dogs, you know, before you get to asking how it would work in a 2-yr-old.)
And as for new ones working better than old ones, I’m not sure that’s a real effect either. The trials all have kids who’ve had YEARS of the old-style treatments, and know exactly what they’ve been having, so the shock of the new may be the effective placebo-push they need. I’ve heard that H2 blockers have become less effective as they lost their magical aura. (Search down Ben Goldacre’s excellent blog http://www.BadScience.net/?p=620)
Constipation affects more folk than bronchiolitis, and probably causes a far greater reduction in the quality of life (when you do the health-of-the-nation sums). Yet we no poo-all about how to treat it really well and effectively. But spend 10,000+ on vaccinations that have minimal effect in RSV. It needs someone to champion it (but not me).
Even if it is mainly placebo though, the great and magical ritual of travelling into the same city that Brum, the supercar superhero, daily rides around, to see the Wise Consultant in the (as-see-on-TV) hospital, is a great way to raise that effect up. Woo to you, sir .. I too will be hoping for a good blast of placebo +./- physiology when I up the dose of docusate on my vincristine-affected patients tomorrow!
(But as to whether you’re an old-fashioned idiot or not I will leave your patients and family to decide … )
Bob Phillips
September 17th, 2008 at 10:35 pm