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Summary This series has addressed the basic segments of a research publication and discussed critical considerations that a reader should make as he progresses through the segments. The questions listed in Figure 3 may be helpful to guide the reader through the evaluation process.

A critical examination of the literature on centrally acting, orally administered skeletal muscle relaxants (SMRs) is presented. The available comparative clinical studies are reviewed, and the pharmacology, metabolism and adverse effects of the oral SMRs are discussed briefly. The drugs covered are carisoprodol, chlorphenesin carbamate, chlorzoxazone, cyclobenzaprine hydrochloride, diazepam, metaxalone, methocarbamol, and orphenadrine citrate. The mechanism of action of these agents is not well defined, and their effects are measured mainly by subjective responses. Thus, acceptable evidence of efficacy is difficult to obtain, especially if clinical studies continue to be designed inadequately. There are inadequate data to support the superiority of any one drug. Further, unique clinical efficacy of any oral SMR in comparison to nonspecific sedation has not been established. Based on subjective responses, all agents, except diazepam, have been shown to be superior to placebo in acute disorders; cyclobenzaprine has not been evaluated in acute conditions. SMRs are less effective in chronic disorders. Combination muscle relaxant-analgesic products appear to be superior to their individual components, but the relative efficacy of these combination products in comparison to combined use of individual sedative and analgesic agents is unknown.

The purpose of this study was to determine if the presence of an in-line 0.22 μ cellulose ester membrane filter would hamper the delivery of a common adult dose of tobramycin sulfate. Solutions of tobramycin sulfate 80 mg in 100 ml D5W were assayed after 30 minute infusions through unfiltered and filtered administration sets; solutions post-flush of filtered sets were also assayed. Assay was done by Emit-QST. The results indicated that there was no significant difference in the delivery of tobramycin sulfate, regardless of the presence of an in-line filter. Solutions post-flush contained about ten percent of the drug, reflecting the amount in solution that remained in the tubing. Since ten percent can alter pharmacokinetic monitoring for patient dosing, a consistent procedure for flushing filtered administration sets should be adopted to enhance accuracy of such determinations.

We have attempted to provide sufficient information to enable the reader to verify that the investigator has used an appropriate statistical test for the evaluation of his study data. We have not discussed the actual calculation of the tests presented. With the wide availability of computers and programmable calculators, it is safe to assume that the investigator has performed the necessary mathematics accurately. Instead of assessing the accuracy of these calculations, the reader should verify that the correct statistical test was chosen in the first place. The astute reader may be surprised at how frequently an incorrect test is used. Merely achieving statistical significance does not characterize the author's data as clinically important. Neither does it, in and of itself, prove one agent superior to another nor prove a cause-and-effect relationship between two variables. When appropriately interpreted, however, statistical analysis can be a very useful and powerful tool in helping to arrive at the "truth."

In this installment on critical evaluation of medical literature, we have discussed the Abstract, Introduction, and Methods sections. A great deal of information is placed in the methodology section of any paper. To critically evaluate a research publication, one must evaluate the methodology, for evaluation of the results of an investigation is meaningless if the methodology is unsound.