|
Andrew M. Ball, MS, PT -> Re: frequently asked questions (April 24, 2000 5:39:00 AM)
|
Forum,
I am getting increasingly irritated with so called professionals on this forum who are on one hand demanding more respect from the general public, trashing chiropractors, asking the healthcare industry to view us as experts in neuromusculoskeletal dysfunction . . . yet don't seem to have the basic evidence-based skills to know when they are spouting nonsense and making the entire profession look like quackary.
If Mcap won't come out in defense of his position and point out Dana's errors, then I sure as heck will . . . because I hope that we can all learn something from this experience and not ever repeat it again on RehabEdge. We are professionals here, and we should start taking a little more responsibility for obtaining the facts via MEDLINE before sarcastically attacking others based upon our own (usually insignificant and incorrect) "expert clinical opinions".
First of all, Mcap went ahead and took a look at the literature before commenting on his position. Dana on the other hand, expected us to challenge Mcap's position based no more than what I can only assume to be her extensive "clinical expertise". The problem with her assumptions based upon her "clinical expertise" is that they wither and die with a quick glance at the literature. The research strongly suggests that obesity is a very minor causative agent in cases of LBP, IF IT IS A CAUSATIVE FACTOR AT ALL. What I found interesting however, is that the reverse scenario may be causative (e.g. chronic low back pain may lead to a higher incidence of eventual obesity). Both the Lake 2000 and Leboeuf-Yde 1999 articles are pretty clear on these points, though my personal favorite is the 56 study literature review by Leboeuf-Yde 2000 in which ", only studies emanating from the general population with a sample size exceeding 3000 were included." That means that 160,000 people were included for analysis in the literature review. The study found only "thirty-two percent of all the studies report a statistically significant positive weak association between body weight and LBP." The Lake study however, would strongly suggest that this relationship was CORRELATIONAL, but not CAUSATIONAL.
So Dana, if Mcap isn't saying it, I sure as heck am. According to the FACTS, people who are overweight, even with excess in the stomach area, are NOT at a greater risk for low back problems!
Submitted in a Respectful, yet Irritated and Frustrated manner by,
Andrew M. Ball, MS, PT
References:
Lake JK, Power C, Cole TJ. Back pain and obesity in the 1958 British birth cohort. cause or effect? J Clin Epidemiol 2000 Mar 1;53(3):245-250.
An association between obesity and back pain has been observed, but the underlying causal direction is uncertain. We examined the temporal sequence among back pain, BMI, and weight gain using data from the 1958 British birth cohort followed to age 33 (4395 men and 4468 women). Heights and weights were measured at ages 7 and 33, and self-reported at age 23. Back pain was classified as: chronic, incident, early onset but recovered, and never. Those with chronic pain gained more weight between ages 23 and 33 than those with no pain, significantly for women (7.39 kg vs. 6.29 kg). Women who were obese at age 23 years had an elevated risk of subsequent back pain onset (32-33 years) (adjusted OR = 1.78). No significant relationships were found for men. The risk of pain onset among women was evident in relation to BMI at baseline (age 23) and cannot therefore be explained by an effect of back pain on adiposity.
Leboeuf-Yde C, Kyvik KO, Bruun NH. Low back pain and lifestyle. Part II--Obesity. Information from a population-based sample of 29,424 twin subjects. Spine 1999 Apr 15;24(8):779-83; discussion 783-4.
STUDY DESIGN: A cross-sectional postal survey of 29,424 twin subjects aged 12-41 years obtained from a population-generated panel. OBJECTIVES: To determine whether obesity is associated with low back pain. SUMMARY OF BACKGROUND DATA: Despite a large number of epidemiologic studies in this area, it is unclear whether obesity and low back pain are positively associated, and if so, whether there is a causal association. METHODS: The association and dose-response connection between body mass index and nonspecific low back pain experienced by subjects in the preceding year were studied. Possible modifying effects of age, gender, type of work, and smoking were investigated. The prevalence of nonspecific low back pain was also studied in monozygotic twin pairs who were dissimilar in body mass index. RESULTS: There was a modest positive association between body mass index and low back pain that increased with the duration of low back pain. The underweight subjects consistently reported lower prevalence of low back pain (odds ratios < 1) than did those higher in weight. The dose-response curve was usually A-shaped. A positive monotonic dose response was apparent mainly in those with long-lasting or recurrent low back pain. The positive association between body mass index and low back pain disappeared when monozygotic twins who were dissimilar in body weight classification were studied. CONCLUSIONS: Obesity is modestly positively associated with low back pain, in particular with chronic or recurrent low back pain. However, because the association is weak, because there is no consistent positive monotonic dose response, and because the link disappears in monozygotic twins who are dissimilar in body mass index, it is unlikely that this association is causal. It is possible, however, that obesity plays a part in the chronicity of simple low back pain. Therefore, those with recurring or long-term low back pain deserve further attention.
Leboeuf-Yde C. Body weight and low back pain. A systematic literature review of 56 journal articles reporting on 65 epidemiologic studies. Spine 2000 Jan 15;25(2):226-37
STUDY DESIGN: A systematic review of the epidemiologic literature. OBJECTIVE: To establish if body weight is truly associated with low back pain (LBP) and whether the link may be causal. SUMMARY OF BACKGROUND DATA: Because obesity and LBP are prevalent in western society, it is of interest to establish whether obesity can induce LBP. METHODS: Fifty-six original research reports, reporting on 65 studies published between 1965 and 1997, were systematically reviewed for the frequency of positive associations between body weight and LBP. In addition, the presence of positive findings was examined in relation to several study characteristics. Based on these results, only studies emanating from the general population with a sample size exceeding 3000 were included in the additional search for causality using some of the classical Bradford-Hill criteria. The review was carried out by the author, blindly at 2 months' interval. RESULTS: Thirty-two percent of all the studies report a statistically significant positive weak association between body weight and LBP. Studies that fulfilled the post hoc criteria never report a rate ratio above 2, but there is possibly a positive biological gradient. These studies had no information on temporality or reversibility and there was no obvious consistency of findings. CONCLUSIONS: Due to lack of evidence, body weight should be considered a possible weak risk indicator, but there is insufficient data to assess if it is a true cause of LBP.
------------------
Andrew M. Ball, MS, PT
MBA/PhD Candidate
|
|
|
|