Investigation 3.4: Botox for Back Pain

Section 11.2 Investigation 3.4: Botox for Back Pain

A 2001 study (Foster, Clapp, Erickson, & Jabbari, Neurology, "Botulinum toxin A and chronic low back pain: A randomized, double-blind study") examined the efficacy of botulinum A (botox, used in various cosmetic and medical procedures) in lower back pain. An excerpt from the journal article follows:

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Thirty-one consecutive patients with chronic low back pain who met the inclusion criteria were studied: 15 received 200 units of botulinum toxin type A, 40 units/site at five lumbar paravertebral levels on the side of maximum discomfort, and 16 received normal saline. Each patient’s baseline level of pain and degree of disability was documented using the visual analogue scale (VAS) and the Oswestry Low Back Pain Questionnaire (OLBPQ). The authors reevaluated the patients at 3 and 8 weeks (visual analogue scale) and at 8 weeks (OLBPQ).
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At 3 weeks, 11 of 15 patients who received botulinum toxin (73.3%) had >50% pain relief vs four of 16 (25%) in the saline group (p = 0.012). At 8 weeks, nine of 15 (60%) in the botulinum toxin group and two of 16 (12.5%) in the saline group had relief (p = 0.009). Repeat OLBPQ at 8 weeks showed improvement in 10 of 15 (66.7%) in the botulinum toxin group vs three of 16 (18.8%) in the saline group (p = 0.011). No patient experienced side effects.
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Checkpoint 11.2.1. Study Type.

Was this an observational study or an experiment? Explain how you are deciding.

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Solution.

This is an experiment because the researchers determined which patients would have the botox and which the saline.

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Checkpoint 11.2.2. Purpose of Control Group.

Explain why it was important to use a comparison ("control") group in this study (rather than simply give botox to all subjects and then measure whether they had experienced pain relief at the end of the study).

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Solution.

To guard against other things changing during the same time period (e.g., back pain just going away over time). We need that to be the same in both groups so that we can further isolate the effects of the botox.

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Checkpoint 11.2.3. Purpose of Normal Saline.

Once a control group is formed, explain the purpose of using "normal saline."

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Solution.

So that participants won’t know which treatment they are receiving, to guard against the "placebo effect."

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Checkpoint 11.2.4. Blinding Subjects.

Explain why it was important for the subjects not to know which treatment they were receiving.

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Solution.

This will equalize any psychological effects from receiving a treatment that you are told will help you feel better.

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Checkpoint 11.2.5. Types of Randomness.

Did this study use random assignment, random sampling, both, or neither, and why is knowing the type(s) of randomness important?

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Solution.

Random assignment (but not random sampling); to create equivalent groups with regard to all variables other than the treatments.

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Checkpoint 11.2.6. Standardized Measurements.

Explain why standardized measurements of pain were used. Do you think the researchers who analyze the effectiveness of Botox should be the ones administering the measurement scales?

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Solution.

To ensure the response variable is measured consistently and without bias (so person taking the measurements also should not know which treatment the patient received). It would be best for someone other than the researchers to administer the measurement scales.

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Checkpoint 11.2.7. Inclusion Criterion.

Why is it important for the published article to outline the "inclusion criterion"?

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Solution.

To help inform as to which population we are willing to generalize the results.

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Definition: Randomized, Comparative, Double-Blind Experiment.

A randomized, comparative, double-blind experiment includes two or more groups being compared, random assignment of "subjects" to groups, and double-blindness (neither the subjects nor the evaluators of the response variable knows which treatment group the subject is in, to guard against the placebo effect and other subjective biases). These types of studies, brought to the forefront of scientific attention by R.A. Fisher (1935), are considered the gold standard for determining cause-and-effect relationships between variables.

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Checkpoint 11.2.8. Feasibility of Experiments.

For the night light and near-sightedness study, would it be feasible to conduct a randomized, comparative, double-blind experiment? Explain.

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Solution.

Probably not feasible to impose the lighting condition on the children.

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Discussion.

Keep in mind, it is not always feasible to design such a study. You also need to be cautious of the Hawthorne effect – people involved in a study sometimes act differently just by virtue of being in a study – and other issues of realism and feasibility, such as:

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Are some ethnic groups less likely to enroll in such a study?
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Maybe those who volunteer for an early vaccine trial differ systematically from those who volunteer for the second drug developed?
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When is it safe to enroll younger children in such drug trials?
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How do we assess the long-term effects of second-hand smoking on pregnant women?
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Subsection 11.2.1 Practice Problem 3.4A

For each of the following research questions, describe how you would design an observational study to address the question and how you would design an experiment. In each case, identify which study you feel is more appropriate. In particular, are there any ethical or logistical issues that might prevent you from carrying out the suggested experiment?

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Checkpoint 11.2.9. Second-Hand Smoke.

Are there effects of second-hand smoke on the health of children?

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Checkpoint 11.2.10. Food Outlets and Spending.

Do people tend to spend more money in stores located next to food outlets with pleasing smells than in stores not located next to such food outlets?

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Checkpoint 11.2.11. Cell Phone Use and Accidents.

Does cell phone use increase the rate of automobile accidents?

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Checkpoint 11.2.12. Bowl Size and Ice Cream.

Do people consume different amounts of ice cream depending on the size of the bowl used?

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Subsection 11.2.2 Practice Problem 3.4B

Researchers conducted a randomized, double-blind trial to determine whether taking large amounts of Vitamin E protects against prostate cancer (Journal of the National Cancer Institute, 1998). To study this question, they enrolled 29,133 Finnish men, all smokers, between the ages of 50 and 69. The men were divided into two groups: One group took vitamin E and a second group took a placebo. The researchers followed all the men for eight years and then determined whether they had developed prostate cancer. They found that participants taking vitamin E were significantly less likely to develop prostate cancer.

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Checkpoint 11.2.13. Randomized.

Explain what "randomized" means in this study and its purpose.

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Checkpoint 11.2.14. Double-Blind.

Explain what "double-blind" means in the context of this study and its purpose.

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Checkpoint 11.2.15. Significantly Less Likely.

Explain what "significantly less likely" means in the context of this study.

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Checkpoint 11.2.16. Cause-and-Effect Conclusion.

Based on this report, is it reasonable to conclude that taking vitamin E causes a reduction in the probability of developing prostate cancer? Explain your reasoning.

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Checkpoint 11.2.17. Generalizability.

Based on this report, to what population is it reasonable to generalize these results? Explain your reasoning.

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Subsection 11.2.3 Practice Problem 3.4C

In a study published in the July 2003 issue of the journal Psychosomatic Medicine, researchers reported that people who tend to think positive thoughts catch a cold less often than those who tend to think negative thoughts. The scientists recruited 334 initially healthy male and female volunteers aged 18 to 54 years through advertisements in the Pittsburgh area, and they first interviewed them over a two-week period to gauge their emotional state, eventually assigning them a numerical score for positive emotions and a numerical score for negative emotions. Then the subjects were quarantined before the researchers injected rhinovirus, the germ that causes colds, into each subject’s nose. The subjects were then monitored for five days for the development of cold-like symptoms. Subjects scoring in the bottom third for positive emotions were three times more likely to catch a cold than those scoring the top third for positive emotions.

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Checkpoint 11.2.18. Study Type and Conclusions.

According to the above definitions, is this an observational study or a randomized experiment? Would it be valid to draw a cause-and-effect conclusion from their results? Explain.

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