Summary Information

The Summary Table lists the trials reviewed for this report, methodological information about the trials, and a “bottom line” summary statement abstracted from the language of the authors. (See Volume 1, Appendix H for listing of included and excluded trials.)

In the first column, the Summary Table presents the trial number (our sequence number), primary author, year of publication, location of trial (either as explicitly stated by the authors, or as deduced by our abstracters based upon the author's address), and a notation if the trial was multi-site. This column also lists the general design of the trial: parallel (i.e., patients assigned to different arms prospectively); matched (i.e., patients assigned to different arms prospectively, based on characteristics of patients already recruited); cross-over (i.e., patients receive one, then the other treatment, in sequence); or split (i.e., patients receive both treatments at the same time).

In the second column, the Summary Table presents the arms of the trial. These are named in terms of the generic names of the treatments used by the investigators. Modifiers, such as “topical,” or dosages are used in the arm names when necessary to distinguish one arm from another within the same trial. All time points at which data were reported in the trial are listed in this column. As was discussed in Volume 1, Chapter 2, we did not abstract all data from all time points; so the listing in this table provides a reference to readers who wish to pursue more data than are listed in our evidence tables.

The third column lists the total sample size plus characteristics of the participants including combined acne severity classification (as described in Volume 1, Chapter 3), age, and gender. The total sample sizes were based, in most cases (243 out of the 275 trials), on data provided by the authors on an intention-to-treat basis. In 18 trials, the authors provided sample size only on the number of subjects completing the trial, and in 5, on subjects somewhere during the course of the trial. In 9 trials, total sample size was provided, but the relation to the course of the study could not be determined. The numbers of males and females listed in the third column were derived from the best information available within the article. Because this was generally not provided on an intention-to-treat basis, the sums of males and females do not always add up to the listed total sample size, and, in some cases, exceed it.

The fourth column lists all outcomes reported by the authors. Not all outcomes listed here are presented in the evidence tables. For example, if the authors reported percentage changes in cyst counts, we do not list both the counts and the percentage change in the evidence tables. The comprehensive listing in this table provides an index to reported outcomes for the interested reader.

The fifth column lists an assessment of the methodological strengths and weaknesses of the trial. Strengths, represented by ↑, are:

• The report provides explicit information showing that the patients were randomized.
• The report provides explicit information that the enroller, treatment provider, or outcomes assessor was blinded to the treatment assignment.
• Five percent or less were lost to followup, based on patients recruited into the trial.
• The trial is generalizable, either because the number of study centers was large or because explicit sampling methods to achieve generalizability were used.

Methodological weaknesses, indicated by ↓, are:

• Treatment assignment was deterministic (i.e., predictable based upon a feature such as day of the week, treatment location, or digit in a medical record number).
• Information in the report shows that patients were not blinded.
• Information in the report shows that the enroller, treatment provider, or outcomes assessor was not blinded to the treatment assignment.
• Data in the report show that there were major losses to followup (> 20 percent of recruited subjects).
• Variable methods of outcome assessment or ascertainment were used in the various arms of the trial.
• Subjects in the arms of the trial were not comparable.
• The trial was not executed as designed.

The last column of the Summary Table presents an “Authors' Bottom Line” statement that paraphrases the conclusions made by the authors.

Presentation of Two- and Three-Arm vs. Multi-Arm Trials

The trials are broken down into two groups:

1. Two- and three-arm trials (180 two-arm trials and 39 three-arm trials), and
2. Trials with more than three arms (9 four-arm trials, 3 five-arm trials, 3 six-arm trials, 2 seven-arm trials, and 1 eight-arm trial).

Group1 comprises the majority of our evidence and data. Because readers may be interested in evaluating different treatments across trials, the evidence tables are presented in terms of two-way comparisons. Each two-arm trial reports on one two-way comparison (A vs. B). Each three-arm trial reports on three two-way comparisons (A vs. B, A vs. C, and B vs. C). Thus Group 1 includes a total of 297 two-way comparisons. The 18 trials in Group 2 with more than three arms contribute an additional 199 two-way comparisons. To make efficient use of space, these are treated differently in the report.

Trials With More Than Three Arms

The tables for these trials parallel those for two- and arm-arm trials. Table Multi.1 is the heading table, Table Multi.2 is the continuous outcomes table, and Table Multi.3 is the discrete outcomes table. The outcomes are listed in a single column, rather than horizontally as pairs. This arrangement enables readers to make their own comparison of all outcomes.