3. Distress: MDQ [%]:

*Indicates outcome at end of menstrual cycle #2, the closest approximation to the single menstrual cycle evaluated in the pilot study.

Other than a graph which displays similar post-MDQ scores of 36-37% for either the SMT or LFM interventions, there is virtually no data offered in the manuscript (other than a statistical statement) to support the authors' contention that there is no significant difference between the two intervention groups with regard to this particular outcome measure.

From the data presented above, it is apparent that:

Pain scores at baseline are 27-37% lower in the full-scale trial as compared to the pilot. This essentially means that patients in the full-scale trial were in less pain and therefore had less of a range with which to assess clinical improvement.

With regards to the LFM, pain scores are significantly (73%) higher at post-intervention for the pilot study as compared to the full-scale trial. This could be a reflection of the greater presenting pain (higher baseline values) of the patients in the pilot study as discussed immediately above (#1). It could also indicate that the sham procedure in the full-scale trial was considerably more effective than in the pilot study. Finally, a combination of the two preceding phenomena could be at play.

With regards to the SMT, post-intervention pain scores appear to be similar in the pilot and full-scale studies.

KDPGF_2a scores appear to be somewhat more erratic, being sharply elevated for the baseline value for the LFM group and depressed at post-intervention in the SMT cohort in the pilot study only. Both the pilot and full-scale studies are similar in that they indicate decreases in the values from pre- to post-intervention in both groups, which are probably not statistically significant from each other.

MDQ scores, while more difficult to fathom, appear to have decreased only half as much from pre- to post-intervention in the SMT cohort in the full-scale trial as compared to the pilot study. This may reflect a difference in the initial pain of participating patients (as suggested in #1 above) and/or a deviation in the type of adjustment delivered or other undetected interaction with the patients.

These inconsistencies point the way to several design flaws evident in the full-scale trial:

Preconditioning of patients: In the full-scale study only, there are indications that the patients admitted into the study were (1) administered a "superficial effluerage" (light body massage) prior to administering either LFM or SMT, and (2) told to refrain from the use of NSAIDs or other analgesics with prostaglandin synthetase-inhibiting activity the week before the expected onset of each menstrual period, which may not be a sufficient period to allow complete washout of the medication. Either of these effects would diminish the severity of symptoms at the outset of the trial (suggested by much of the data presented above), diminish any clinical improvements obtained at post-treatment, and mask possible differences between the two treatment groups.

Nature of the sham adjustment: Overlap of the mimic and SMT effects has been consistently referred to in both the pilot and full-scale studies. Even though sham procedures were not to have exceeded 400 Newtons while SMT procedures typically involved thrusts exceeding 750 Newtons, a growing body of evidence suggests that nonspecific effects observed in the sham procedure as well as devising a technique which stands clearly apart from chiropractic intervention both require far more attention than previously shown. Perhaps the fairest single statement in Dr. Brennan's entire paper is the final sentence, which indicates that the results of this trial ". . .are strong evidence that either the low force mimic maneuver was an insufficient placebo treatment or, in fact, that manual therapy does not relieve the pain in women with primary dysmenorrhea [italics added]."

Lack of waiting control group: Despite the fact that the blinding itself was effective in masking the patients' perceptions of sham and actual treatments, no group was included which delayed or withheld physical contact with the patient. It would seem rather disingenuous for the authors to have suggested in the paper that the level of available funding precluded including this valuable control, as if such funding agencies as the Foundation for Chiropractic Education and Research (FCER) and NCMIC Group, Inc. (NCMIC) might somehow be at fault. In the grant application stages to FCER and NCMIC, waiting list controls were in fact originally stipulated by the authors but were unfortunately dropped during the course of the study.

Effects of exercise: Since exercise may have a relieving, aggravating, or no effect upon menstrual pain in different women, it was proscribed for 24 hours prior to treatment in the pilot study. No such provision could be found in the full-scale trial publication. It is possible that exercise within a 24 hour period of treatment in an unknown number of participants confounded the results in the later study.

To summarize, the recent full-scale clinical trial fails to distinguish between two possible alternatives: (1) a sham procedure that is an inadequate placebo treatment, and (2) the possibility that the side-posture adjustments administered in this investigation were not effective for

relieving pain or lowering prostaglandin levels in women with primary dysmenorrhea. Our hope is that further research will help in distinguishing between these alternatives in the very near future.

REFERENCES:

1. Hondras MA, Long CR, Brennan PC. "Spinal manipulative therapy vs. a low force mimic maneuver for women with primary dysmenorrhea: A randomized, observer-blinded, clinical trial." Pain. 1999. In press.