The Journals of Gerontology Series A: Biological Sciences and Medical Sciences 57:M544-M550 (2002)
© 2002 The Gerontological Society of America
A Community-Based Study of Postmenopausal White Women With Back and Leg Pain
Health Status and Limitations in Physical Activity
Molly T. Vogta,b,
William C. Lauermanc,
Mark Chirumbolea and
Lewis H. Kullerb
a Departments of Orthopaedic Surgery, University of Pittsburgh, Pennsylvania
b Departments of Epidemiology, University of Pittsburgh, Pennsylvania
c Department of Orthopaedic Surgery, Georgetown University, Washington, DC
Molly T. Vogt, Department of Orthopaedic Surgery, Suite 1010, 3471 Fifth Avenue, Pittsburgh, PA 15213 E-mail: vogtm{at}msx.upmc.edu.
 |
Abstract
|
|---|
Background. The objective of this study was to determine the prevalence of lower back pain and associated leg pain/numbness in postmenopausal Caucasian women and the relationship of these symptoms to health status and function.
Methods. A convenience sample of 573 white women enrolled in the Observational Study of the Women's Health Initiative (WHI) in Pittsburgh completed a questionnaire on low back pain (LBP) and leg pain (LP) and its impact on their daily activity. For data analysis, this information was merged with that obtained under the standard WHI protocol.
Results. Almost half of the women (49%) reported having had LBP during the previous month: 8% had LBP only, while 41% had both LBP and LP. In 9% of women, the leg and back symptoms were alleviated by sitting. Among women with LBP during the previous month, those who also had leg pain were five times more likely to have had functional limitations, two to four times more likely to have consulted a clinician or taken medications, and more likely to have had prior spinal surgery or hospitalization than the women with no LP. Based on the Short Form-36, women with LBP/LP had significantly lower scores for physical function, physical role, and bodily pain than women with no LBP or with LBP alone.
Conclusions. Low back pain that radiates into the hip, buttock, or leg is relatively common in postmenopausal Caucasian women living in the community and is associated with decreased physical health status and with physical limitations.
THE etiology of back pain is not well delineated but among older individuals, back pain is related, at least in part, to degenerative changes in the spine (1)(2). The degenerative process typically involves the intervertebral discs, facet joints, vertebral bodies, and spinal ligaments and may result in narrowing (stenosis) of the spinal canal, particularly in the cervical or lumbar regions of the spine. In the lumbar region, this narrowing may result in compression of the cauda equina or the spinal nerves, giving rise to back pain that radiates down into the buttocks and leg (3). Numbness, tingling, or weakness may also occur in the lower back, buttocks, and leg, and, ultimately, ambulation may become severely affected. Spinal flexion usually relieves these symptoms to some degree, and most patients report that their pain decreases when they are seated.
During the 1950s, the population prevalence of back and radiating leg pain in the United Kingdom was reported to increase with increasing age (4). Among women, the highest prevalence (5%) occurred after age 65 years. However, more recent studies (5)(6)(7)(8), most carried out among working age adults, have suggested that the prevalence of these symptoms may be several times higher than previously thought.
The current research project was undertaken to determine the prevalence of lower back pain (with and without associated leg pain and numbness) and its relationship to health status and function among women enrolled in the Women's Health Initiative (WHI) Observational Study at the University of Pittsburgh WHI clinic.
|
Methods
|
|---|
In 1994, the Design and Analysis Committee of the WHI granted approval for the authors of this article to conduct an ancillary study to assess back and leg pain symptoms occurring among a convenience sample (n = 573) of women enrolled in the Observational Study of the Women's Health Initiative at the University of Pittsburgh WHI clinic. Approval of the University of Pittsburgh Institutional Review Board was obtained in 1994.
WHI Study Population
The WHI began in 1992 and has three components: the Clinical Trial program composed of three randomized clinical trials, an observational study, and a separate community intervention study. There are 40 WHI clinical centers nationwide, and, overall, 68,133 postmenopausal women (aged 50 to 79 years) are enrolled in the Clinical Trial and 93,676 in the Observational Study. A detailed description of the WHI study has been previously published (9).
Data Collected Using the Standard WHI Protocol
At baseline, WHI participants completed standard questionnaires designed to elicit information on demographic and lifestyle factors as well as medical history. In addition, participants were asked about depressive symptoms occurring during the week prior to the clinic visit and in the past. The Short Form-36, one of the most widely used generic health status questionnaires in health research, was also completed (10). It consists of 36 multiple-choice questions, aggregated into eight subscales: physical function, role limitations due to physical health problems, bodily pain, general health, vitality, social functioning, role limitations due to emotional problems, and mental health. These subscales may also be aggregated to derive the Physical Component Summary (PCS) and Mental Component Summary (MCS) scales (11)(12). Individual questions within the SF-36 provided detailed information about specific functional limitations.
During the clinic visit, participants were weighed (to the nearest 0.1 kg) on a balance beam scale while wearing indoor clothes, but no shoes. Height was recorded (to the nearest 0.1 cm) using a wall-mounted stadiometer and a standard held-expiration technique. Body mass index (BMI) was calculated as the weight (kilograms) divided by height (meters) squared.
Ancillary Study Procedures
A convenience sample (n = 573) of women enrolled in the Observational Study at the WHI clinical center in Pittsburgh during a 1-year period, 1994–1995, were asked to complete an additional questionnaire during their baseline clinic visit. This sample comprised 31% of the total women (N = 1852) enrolled in the Observational Study at the University of Pittsburgh.
The back pain questionnaire elicited information regarding their lifetime history of low back pain (LBP) (none, 1–5, more than 5 episodes, continuous pain) and prior treatment for LBP (surgery, hospitalization, injections). The women were also asked whether they had had LBP during the previous month. Those who responded affirmatively were asked whether the pain had radiated into their buttocks or legs; whether they experienced numbness or tingling; whether symptoms were better/worse/unchanged when lying in bed, sitting in a chair, standing, and walking; whether symptoms were severe enough to cause them to limit their activity (yes/no), confine them to bed (yes/no), take medication for the pain (yes/no), or visit a physician or chiropractor (yes/no).
Data Analysis
Women were categorized into four groups by symptomatic status: no LBP during the month prior to the clinic visit; only LBP; LBP and leg pain, tingling, or numbness, not relieved by sitting; LBP and leg pain, tingling, or numbness that is relieved by sitting. For continuous variables, the statistical significance of differences between groups was assessed using general linear modeling techniques. Multivariate linear regression was used to adjust for potential confounders. For categorical variables, the chi-square statistic was used to test for the statistical significance of differences between groups.
Logistic regression was used to determine the age and age/BMI/depression-adjusted odds ratio among women across the symptom groups. Age and BMI were used in these models as continuous variables. The categorical variable "have you felt depressed within the last week" (none/1 to 2 days/3 to 4 days/most days depressed) was included in the model using dummy variables.
|
Results
|
|---|
Prevalence of Back and Leg Pain
About half (49.3%) of the women reported having had at least one episode of LBP during the month prior to the clinic visit; 8.2% had LBP only, while 41.1% had accompanying leg pain. In 9.1%, the leg and back symptoms were alleviated when the women sat down. The prevalence of LBP and of LBP/LP (LBP with leg pain) decreased with increasing age (Fig. 1). Among women with LBP, 38% reported that their LP did not radiate below the knee, while 46% had below knee pain (Table 1 ).
View larger version (18K):
[in this window]
[in a new window]
|
Figure 1. Percentage of white Women's Health Initiative women reporting low back pain (LBP), LBP with leg pain (LBP/LP), and LBP/LP improved by sitting during the past month by age group.
|
|
View this table:
[in this window]
[in a new window]
|
Table 1. Leg Symptoms Among 278 White Postmenopausal Women Experiencing Low Back Pain During the Previous 30 Days
|
|
Characteristics of Women With Low Back Pain
Women who reported back pain and leg symptoms were on average about a year younger than those with either no recent episodes of back pain or back pain without leg symptoms (Table 2 ). Although the percentage of body fat was similar in all groups of women, those with LBP/LP weighed 2 to 3 kg more and had a higher BMI. The overall proportion of women who smoked cigarettes (7.7%), had graduated from college (37%), and were currently employed either full or part time (36%) did not vary by back pain status.
History of Spinal Problems
Compared to women with no back pain during the previous month, those with LBP or LBP/LP were more likely to report recurrent episodes of LBP during their lifetime (20% vs 70%) (Table 3 ). Similarly, women with LBP/LP were approximately four times more likely to have previously been hospitalized for back pain or to have had injections for back pain and were twice as likely to have had spinal surgery (Table 3 ).
Effect of Recent Spinal Problems on Activity Limitation and Health Resource Utilization
Among those women who reported back pain during the previous month, those with both LBP and LP were twice as likely to have consulted a clinician about that pain and/or to have stayed in bed because of that pain and were three to four times more likely to have taken medication or to report that their back pain limited daily activity (Table 4 ).
View this table:
[in this window]
[in a new window]
|
Table 4. Effect of Back Pain and Related Symptoms on Daily Life Among Postmenopausal White Women by Spinal Symptoms Reported Within Past Month
|
|
Impact on Daily Activities
The SF-36 was used to obtain a generic assessment of health status in this cohort (i.e., the women answered this questionnaire with respect to their overall health, not limiting their responses to the impact that back pain had on their health status and function). Based on the responses to the 10 physical function items on the SF-36, women with radiating leg pain were more likely to report daily activity limitations than were those who had no LBP or LBP without LP (Table 5 ). For the least physically demanding activities (walking one block, bathing, and dressing self), no differences were detectable across the groups of women, but for the more demanding activities (walking several blocks, climbing stairs, lifting, etc.), the likelihood of limitation was increased two- to three-fold among those with leg pain (Table 5 ). Similarly, several questions from the SF-36 about physical limitations experienced during the past week also revealed that the women with LP were three- to four-fold more likely to report limitations (Table 5 ).
View this table:
[in this window]
[in a new window]
|
Table 5. Recent Functional Limitations Among Postmenopausal White Women by Spinal Symptoms Reported Within Past Month
|
|
Health Status
The PCS scale derived from the SF-36 was significantly lower (0.5 standard deviation) among women with radiating leg pain (Table 6 ) compared to those who had reported no LBP during the past month. The MCS did not vary across the groups. Inspection of the scores obtained on the eight domains of the SF-36 revealed that women with radiating leg pain generally had lower scores than the women with no back pain or only LBP (Fig. 2). These differences are statistically significant (p < .001) and range from 0.4 to 0.7 SD. The values obtained on the general health domain of the SF-36 do not differ across the groups of women.
View larger version (16K):
[in this window]
[in a new window]
|
Figure 2. Short Form-36 scores for white women reporting no low back pain (no LBP), LBP, LBP with leg pain (LBP/LP), and LBP/LP improved by sitting during the past month. All scores are adjusted for age and body mass index. PF = physical function; RP = role limitations due to physical health problems; BP = bodily pain; GH = general health; VT = vitality; MH = mental health; SF = social functioning; RE = role limitations due to emotional problems.
|
|
|
Discussion
|
|---|
The results of this study indicate that low back pain that radiates into the hip, buttock, or leg imposes a substantial burden on the lifestyle and daily functioning of postmenopausal white women. About 40% of the women studied reported that this type of pain had occurred within the previous month, and those women had lower measures of physical health (based on the SF-36) than women reporting either no LBP or pain confined to the lower back. They were also more likely to experience activity limitations, use medications, and visit a physician or chiropractor. Almost two thirds of the women with LBP during the previous month reported multiple episodes of pain throughout their lives, but those with pain radiating into their legs were two to four times more likely to have been hospitalized or to have had spinal injections for back problems.
Almost everyone in the population experiences lower back pain at some time during their lives, but there is relatively little published research on the prevalence of LBP or its impact on the quality of life in older individuals (2). A recent review noted that LBP prevalence estimates in people 65 years and older vary widely among studies, ranging from 14% to 51%, and that women generally have a somewhat higher prevalence than men (2). There is currently no gold standard definition for LBP (13), and to some extent the wide range in estimated prevalence may be explained by the varying definitions of "low back pain" used in these studies.
Almost half (49%) of the women in our study reported experiencing LBP during the month prior to the clinic visit. This figure is relatively high but is similar to that reported for the 6-month LBP prevalence among women 65 years and older (14). To check for recruitment bias in our back pain study, we compared the prevalence of LBP reported on the standard WHI forms among all women enrolled in the WHI Observational Study at the Pittsburgh clinic (N = 1852) and among the women in our ancillary study (n = 573). These prevalences were similar (55.8% vs 55.4%), indicating that women with LBP had not preferentially enrolled in the ancillary study.
In the current study, women with LBP were categorized as having/not having pain that radiated to the hip, buttocks, or lower extremity. During a typical orthopedic clinical examination, patients are asked whether their pain is relieved by sitting (15). A positive response suggests that nerve root compression in the cauda equina, the definition of lumbar spinal stenosis, may be occurring. Women in this study were also categorized by their response to this question, and 9% had symptoms suggestive of spinal stenosis. However, measures of their health status did not differ from those of women with leg pain not relieved by sitting. Overall, women with pain radiating into the leg had significantly worse physical health status than women who had no back pain or LBP alone. This finding is similar to that reported for back pain patients with radiating leg pain (15)(16)(17)(18), but has not been previously reported among a community-based cohort.
The mean PCS value for women with no LBP was 48.0 and that for all women with LBP/LP was 42.5. These scores indicate that the women in this cohort with no back pain are at the 31st percentile of the U.S. population with respect to physical health, while those with LBP/LP are at the 19th percentile (12). The difference in PCS between these two groups of women is approximately 0.5 SD or 5.5 points. This is similar to previous estimates of the health burden associated with LBP/LP obtained from cross-sectional studies, that is, 4.38 (measured in the Medical Outcomes Study cohort) and 3.75 (measured in the general U.S. population) (12). The health burden (assessed by the SF-36) associated with LBP/LP is substantial and is similar to that experienced by individuals with angina, chronic lung disease, or diabetes (12).
This research has several limitations. First, women electing to participate in WHI may be healthier than those in the population of the Pittsburgh area as a whole. However, the mean PCS and MCS scores for women in this study (45.63 and 51.6) are similar to those reported for women of the same age in the U.S. population (45.33 and 51.72) (12). If a "healthy volunteer" bias exists, it would be likely to lead to an underestimation of the impact of leg and back pain among postmenopausal women (i.e., those with more severe back problems, cardiovascular disease, arthritic conditions, etc., are less likely to participate). In addition, the current study cohort is relatively small, and stratification into multiple levels of pain involvement severely decreases our statistical power to detect variations across these pain levels. Third, the cohort is composed of white postmenopausal women residing in an urban area of Pennsylvania. The results obtained may not be generalizable to women from rural areas or other urban regions of the country. Fourth, the results are based on self-reported pain. No attempt was made to diagnose the underlying conditions. Leg pain may be the result of comorbid conditions unrelated to spinal cord or nerve compression. For instance, hip pain could be due to hip arthritis and below knee pain to peripheral atherosclerosis. Finally, the study is cross-sectional in nature and, therefore, cannot establish causal relationships between back and leg pain and other measured variables. However, the cross-sectional associations between variables do suggest a variety of hypotheses to be tested in future longitudinal studies.
Patients with spinal disorders have a high degree of physical impairment. In a recent study of more than 17,000 patients enrolled in the National Spinal Network (NSN) Database, the PCS of these patients was 2.0 SD lower than the norm for the U.S. population (19). The authors of the NSN study suggest that physicians who treat spine patients may have underestimated the devastating effects that these disorders have on the quality of life for their patients. Similarly, among the relatively healthy postmenopausal women in the current study, low back pain that radiates into the leg is associated with a marked decrease in physical function and an increased utilization of health care resources.
|
Acknowledgments
|
|---|
This research was supported in part by Grant N01-WH-3-2112 from the National Institutes of Health.
Program Office: (National Heart, Lung, and Blood Institute, Bethesda, MD) Jacques E. Rossouw, Linda Pottern, Shari Ludlam, Joan McGowan, Nancy Morris.
Clinical Coordinating Center: (Fred Hutchinson Cancer Research Center, Seattle, WA) Ross Prentice, Garnet Anderson, Andrea LaCroix, Ruth Patterson, Anne McTiernan; (Bowman Gray School of Medicine, Winston-Salem, NC) Sally Shumaker, Pentti Rautaharju; (Medical Research Labs, Highland Heights, KY) Evan Stein; (University of California at San Francisco, San Francisco, CA) Steven Cummings; (University of Minnesota, Minneapolis, MN) John Himes; (University of Washington, Seattle, WA) Susan Heckbert.
Clinical Centers: (Albert Einstein College of Medicine, Bronx, NY) Sylvia Wassertheil-Smoller; (Baylor College of Medicine, Houston, TX) Jennifer Hays; (Brigham and Women's Hospital, Harvard Medical School, Boston, MA) JoAnn Manson; (Brown University, Providence, RI) Annlouise R. Assaf; (Emory University, Atlanta, GA) Lawrence Phillips; (Fred Hutchinson Cancer Research Center, Seattle, WA) Shirley Beresford; (George Washington University Medical Center, Washington, DC) Judith Hsia; (Harbor-UCLA Research and Education Institute, Torrance, CA) Rowan Chlebowski; (Kaiser Permanente Center for Health Research, Portland, OR) Cheryl Ritenbaugh; (Kaiser Permanente Division of Research, Oakland, CA) Bette Caan; (Medical College of Wisconsin, Milwaukee, WI) Jane Morley Kotchen; (Medstar Research Institute, Washington, DC) Barbara V. Howard; (Northwestern University, Chicago/Evanston, IL) Philip Greenland; (Rush-Presbyterian St. Luke's Medical Center, Chicago, IL) Henry Black; (Stanford Center for Research in Disease Prevention, Stanford University, Stanford, CA) Marcia L. Stefanick; (State University of New York at Stony Brook, Stony Brook, NY) Dorothy Lane; (The Ohio State University, Columbus, OH) Rebecca Jackson; (University of Alabama at Birmingham, Birmingham, AL) Cora Beth Lewis; (University of Arizona, Tucson/Phoenix, AZ) Tamsen Bassford; (University at Buffalo, Buffalo, NY) Maurizio Trevisan; (University of California at Davis, Sacramento, CA) John Robbins; (University of California at Irvine, Orange, CA) Allan Hubbell; (University of California at Los Angeles, Los Angeles, CA) Howard Judd; (University of California at San Diego, LaJolla/Chula Vista, CA) Robert D. Langer; (University of Cincinnati, Cincinnati, OH) James Liu; (University of Florida, Gainesville/Jacksonville, FL) Marian Limacher; (University of Hawaii, Honolulu, HI) David Curb; (University of Iowa, Iowa City/Davenport, IA) Robert Wallace; (University of Massachusetts, Worcester, MA) Judith Ockene; (University of Medicine and Dentistry of New Jersey, Newark, NJ) Norman Lasser; (University of Miami, Miami, FL) Mary Jo O'Sullivan; (University of Minnesota, Minneapolis, MN) Karen Margolis; (University of Nevada, Reno, NV) Sandra Daugherty; (University of North Carolina, Chapel Hill, NC) Gerardo Heiss; (University of Pittsburgh, Pittsburgh, PA) Lewis Kuller; (University of Tennessee, Memphis, TN) Karen C. Johnson; (University of Texas Health Science Center, San Antonio, TX) Robert Schenken; (University of Wisconsin, Madison, WI) Catherine Allen; (Wake Forest University School of Medicine, Winston-Salem, NC) Electra Paskett; (Wayne State University School of Medicine/Hutzel Hospital, Detroit, MI) Susan Hendrix.
Received January 17, 2002
Accepted January 18, 2002
|
References
|
|---|
- Videman T, Battié MC, 1996. A critical review of the epidemiology of idiopathic low back pain. Weinstein JN, Gordon SL, , ed.Low Back Pain: A Scientific and Clinical Overview 317-332. American Academy of Orthopaedic Surgeons, Rosemont, IL.
- Bressler HB, Keyes WJ, Rochon PA, Badley E, 1999. The prevalence of low back pain in the elderly. Spine. 24:1813-1819. [Medline]
- Andersson GBJ, 1996. Epidemiology of spinal stenosis. Weinstein JN, Gordon SL, , ed.Low Back Pain: A Scientific and Clinical Overview 637-641. American Academy of Orthopaedic Surgeons, Rosemont, IL.
- Lawrence JS, ed. Rheumatism in Populations. London, England: Heinemann Medical; 1977.
- Heliovaara M. Epidemiology of Sciatica and Herniated Lumbar Intervertebral Disc. Helsinki, Finland: Social Insurance Institution; 1988.
- Videman T, Heikkliä JK, Koskenvuo M, et al. 1990. The role of environmental factors in the development of back pain and sciatica: an epidemiological study with adult twin pairs. Orthop Trans. 14:6-11.
- Kelsey JL, 1978. Epidemiology of radiculopathies. Adv Neurol. 19:385-398. [Medline]
- Heliovaara M, 1987. Body height, obesity, and risk of herniated lumbar intervertebral disc. Spine. 12:469-472. [Medline]
- The Women's Health Initiative Study Group1998. Design of the Women's Health Initiative Clinical Trial and Observational Study. Control Clin Trials. 19:61-109. [Medline]
- Ware JE, Snow KK, Kosinski M, Gandek B. SF-36 Health Survey Manual & Interpretation Guide. Boston, MA: The Health Institute, New England Medical Center; 1993.
- McHorney CA, Ware JE, Raczek AE, 1993. The MOS 36-Item Short-Form Health Survey (SF-36): II. Psychometric and clinical tests in validity in measuring physical and mental health constructs. Med Care. 31: (3) 247-263. [Medline]
- Ware JE, Kosinski M, Keller SD. SF-36 Physical and Mental Health Summary Scales: A User's Manual. Boston, MA: The Health Institute; 1994.
- Spitzer WO, Leblanc FE, Dupuis M, 1987. Scientific approach to the assessment and management of activity-related spinal disorders: a monograph for clinicians—report of the Quebec Task Force on Spinal Disorders. Spine. 12: (suppl) S16-S21.
- Von Korff M, Dworkin SF, Resche LL, Kruger A, 1988. An epidemiologic comparison of pain complaints. Pain. 32:173-183. [Medline]
- Wipf JE, Deyo RA, 1995. Low back pain. Med Clin North Am. 79:231-246. [Medline]
- Selim AJ, Ren XS, Fincke G, et al. 1998. The importance of radiating leg pain in assessing health outcomes among patients with low back pain. Spine. 23:470-474. [Medline]
- Deyo RA, Tsui-Wu YJ, 1987. Functional disability due to back pain: a population-based study indicating the importance of socioeconomic factors. Arthritis Rheum. 30:1247-1253. [Medline]
- Patrick DL, Deyo RA, Atlas SJ, Singer DE, Chapin A, Keller RB, 1995. Assessing health-related quality of life in patients with sciatica. Spine. 17:1899-1909.
- Fanuele JC, Birkmeyer NO, Abdu WA, Tosteson TD, Weinstein JN, 2000. The impact of spinal problems on the health status of patients. Spine. 25:1509-1514. [Medline]
Top
Abstract
Methods
