The Effect of High Body Mass Index on the Prevalence of Lower Back and Hip Pain of Physical Therapy Patients

Introduction The percentage of Americans who are overweight and obese has significantly increased in the last 20 years. In 2012, 69.2 percent of Americans were overweight ((Body Mass Index (BMI) of over 25)), and 35 percent were considered obese (BMI over 30) (Shields, Carron and Oden, 2011). It is estimated that roughly 80 percent of the United States population will experience lower back pain during adulthood (Mirtz and Greene, 2005). Patients with a higher Body Mass Index carry more weight on the facets of the vertebrae in their spine, and significantly less weight on the body of the vertebrae, which alters the desired even weight distribution. Overweight and obese patients also place more strain on lumbar fascia which attaches to the hip and abdominal musculature and have increased risk of compression of the spine; further increasing their level of pain (Schuller, Charles and Steib, 2011). Studies have shown that increased weight and the resulting anterior tilt of the pelvis in overweight individuals make them more prone to lower back pain (Mirtz and Greene, 2005).

Methods Height (in), weight (lbs) and birthdate were collected from 37 (12 male and 25 female) physical therapy patients who were diagnosed with lower back and hip pain. Patients were from 3 separate physical therapy practices. In order to do determine the pain index in lower back and hip pain patients, 15 individuals were surved for highest pain level rating on a 1-10 scale with 10 being the highest level of pain. These pain indices were then plotted against the patients BMI level to determine an association. The Body Mass Index was calculated for each patient using the formula [Weight (lbs)/Height (in)2]×703. Patients were then grouped into three BMI categories: Normal (20-24.9), Overweight (25-29.9) and Obese (30+).

Results

Results & Discussion

Percentages of overweight and obese individuals were significantly higher in physical therapy patients with lower hip and back pain than in the national and Pennsylvania averages (Table 1). The study showed an association between an elevated BMI and patients with lower back and hip pain. The association between lower hip and back patients pain indices and their respective BMI was not significant (Figure 1). A negative association was seen between pain indices and BMI such that patients reported a lower pain level as the BMI increased. A possible explanation for this may be that as BMI increases other issues that result from the increased BMI may result in altering the individuals ability to perceive or differentiate their pain levels. Another possible explanation is that as an individual’s BMI increases they adopt a more stationary lifestyle that results in lower pain indices as not to aggravate their body.

Literature Cited• Mirtz, Timothy A and Greene, Leon. Chiropractic and Osteopathy. “Is

obesity a risk factor for low back pain? An example of using the evidence to answer a clinical question”. 2005; 13: 2.

• Schuller, Sébastien. Charles, Yann Philippe. and Steib, Jean-Paul. European Spine Journal. “Sagittal spinopelvic alignment and body mass index in patients with degenerative spondylolisthesis”. 2011. May; 20(5): 713–719.

• Shields M., Carroll M.D., Ogden C.L. “Adult Obesity Prevalence in Canada and the United States.” Advances in Nutrition: An International Review Journal 2.4 (2011): 368-69. Print.

Future Studies• Larger sample size • Closer gender distribution • Wider range of BMI’s• Consider other pain assessments that include how pain

affects functions/abilities.

Table 1. Percentage of normal, overweight and Obese individuals at national, state and study levels.

Objectives• To determine if the percentage of obese

and overweight individuals in physical therapy is significantly higher that the national average

• To determine if an elevated BMI is associated with higher pain indices in back and hip pain patients.

Emily Hail Department of Biological Sciences. York College of Pennsylvania

Acknowledgments I gratefully thank Dr. Bobbi Patton and Dr. Ronald Kaltreider for their mentorship and generous assistance in the preparation and performance of this study. I would like to thank Dr. Karl Kleiner for his assistance with the statistics, editing and submission of this thesis.

% Normal (18.5-24.9)

% Overweight (25+)

% Obese (30+)

National Average

30.8 69.2 35.9

Pennsylvania Average

35 65 28.6

Study Average

29.7 70.3 40.5

0 5 10 15 20 25 30 35 40 450

2

4

6

8

10

BMI

Pai

n In

dex

Figure 1. Relationship between body mass index (BMI)and pain index for paitents with lower back and hip pain(r=-0.2292, P=0.5223, Spearman's rank correlation).