Members of the REST team have published a new meta-analysis of Z drugs in the British Medical Journal (http://www.bmj.com/content/345/bmj.e8343).
The effectiveness of newer sleeping tablets, the Z drug (or non-benzodiazepine) hypnotics has been questioned because of publication and reporting bias in previous meta-analyses and the extent of the placebo response to hypnotics.
The study team analysed data submitted to the US Food and Drugs Administration (FDA) for drug approval. Publication bias was eliminated by combining the results of all pharmaceutical industry (‘pharma’) studies, published or unpublished, where a Z drug was compared to placebo. There were 13 studies containing 65 different comparisons of drug-placebo by type of outcome, type of drug, and dose, with 4378 participants from different countries, treatment lengths (mostly up to 30 days), and study years.
The study showed that Z drugs reduced the time to fall asleep in people with primary insomnia, both subjectively and measured in a sleep lab but the effects were relatively small (about 22 minutes). The placebo response was similar to the drug effect and the two together produced a reasonable clinical response. Around half the effect of the drug was a placebo response, which means the placebo response is important in this type of treatment.
There was no demonstrable effect of Z drugs on other outcomes, mainly because these studies tended not to measure sleep quality, daytime sleepiness or other outcomes which may be just as or more important to patients. Z drugs were more effective with larger doses but, more surprisingly, had greater effects in younger or female patients regardless of type of drug. Pharma trials tend to be more positive than non-pharma trials so we have to bear in mind that they tend to overestimate drug effects.
Around a fifth of older people get side effects from sleeping tablets and around one in a hundred will have a fall, fracture or road traffic accident after using them short-term. Cognitive behavioural therapy for insomnia works as well as sleeping tablets in the short term and is better and safer in the longer term so increasing access to these treatments for those who would benefit from them continues to be a priority.
Huedo-Medina TB, Kirsch I, Middlemass J, Klonizakis M, Siriwardena AN. Effectiveness of non-benzodiazepine hypnotics in treatment of adult insomnia: meta-analysis of data submitted to the Food and Drug Administration. BMJ 2012:345: e8343 (http://www.bmj.com/content/345/bmj.e8343).