BMJ 1995;310:1138 (29 April)

Letters

Study quoted had flawed design

EDITOR,--In their meta-analysis of the efficacy of quinine for night cramps Malcolm Man-Son-Hing and George Wells analysed six trials that met strict criteria for design.1 Included in these six trials is one carried out by one of us (NRD) in 1991 on patients from his practice and a practice in Southampton.2 It is surprising that the authors included the data from this trial, since it was stated clearly that the results showed that the design of the trial was invalid. As the table shows, there was a clear carryover effect: patients who received quinine first, followed by placebo, experienced more nights with cramp in the placebo period than did those who received the placebo first. The test for carry over is significant (Mann-Whitney W=247.5, P<0.05). 


Proportion of nights with cramp
-----------------------------------------------------
            1st Period    2nd Period    Both periods
Treatment    (n=750)       (n=750)        (n=1500)
-----------------------------------------------------
Quinine      203 (27)      104 (14)       300 (20)
Placebo      . . . [Full text of this article]


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Relevant Article

Meta-analysis of efficacy of quinine for treatment of nocturnal leg cramps in elderly people
Malcolm Man-Son-Hing and George Wells
BMJ 1995 310: 13-17. [Abstract] [Full Text]

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