Virginia A. Aparicio, BSc, Francisco B. Ortega, PhD,, and Manuel Delgado-Fernandez, PhD*

Transcription

1 Original Article The 6-Minute Walk Test in Female Fibromyalgia Patients: Relationship With Tenderness, Symptomatology, Quality of Life, and Coping Strategies From the *Department of Physical Education and Sport, School of Physical Activity and Sports Sciences; Department of Physical Education and Sport, School of Education Sciences, University of Seville, Spain; Department of Biosciences and Nutrition, Unit for Preventive Nutrition at NOVUM, Karolinska Institutet, Huddinge, Sweden; Department of Physiology, School of Pharmacy and Institute of Nutrition and Fodd Technology; and ; Department of Physiology, School of Medicine, University of Granada, Granada, Spain. Address correspondence to Ana Carbonell-Baeza, PhD, Departamento de Educacion Fısica y Deportiva, Universidad de Granada, Carretera de Alfacar, s/n, 18011, Granada, Spain. anellba@ ugr.es Received October 3, 2010; Revised January 2, 2011; Accepted January 2, Supported by the Spanish Ministry of Education (grant nso. AP and EX ) and the Spanish Ministry of Science and Innovation (BES ), and Ramon y Cajal (RYC ) /$36.00 Ó 2011 by the American Society for Pain Management Nursing doi: /j.pmn Ana Carbonell-Baeza, PhD, *, Jonatan R. Ruiz, PhD, *, - ABSTRACT: Virginia A. Aparicio, BSc, Francisco B. Ortega, PhD,, and Manuel Delgado-Fernandez, PhD* The purpose of this study was to examine the relationship between the 6-minute walk test (6-MWT) and tenderness, symptomatology, quality of life, and coping strategies in women with fibromyalgia. One hundred eighteen women with fibromyalgia aged 51.9 ± 7.3 years participated in the study. The examination included the 6-MWT, tender points, and the following questionnaires: Fibromyalgia Impact Questionnaire (FIQ), Short-Form Health Survey 36 (SF-36), and Vanderbilt Pain Management Inventory. Fair correlations between the 6-MWT and the subscales of physical impairment (FIQ) and physical function (SF- 36) were observed (rl0.365 and 0.347, respectively, both p<.001). The 6-MWT showed a weak relationship with tenderness (r and L0.191 for algometer score and tender points count, respectively, both p <.05). The relationship between the 6-MWT and global score of FIQ, and FIQ subscales of pain and fatigue were weak (rl0.201, L0.211, and L0.226, respectively, all p <.05). The 6-MWT showed a weak relationship with bodily pain and vitality scales of SF-36 (r and 0.258, respectively, both p ¼.005) and with passive and active coping strategies (rl0.255 and 0.223, both p<.05). This study in women with fibromyalgia shows significant relationships, ranging from weak to fair, between the 6-MWT and tenderness, symptomatology, quality of life, and coping strategies. These findings indicate that functional capacity, as assessed by the distance walked in 6 minutes, might be important when planning the assessment, treatment, and monitoring of patients with fibromyalgia. Ó 2011 by the American Society for Pain Management Nursing Pain Management Nursing, Vol-, No-(--), 2011: pp 1-7

2 2 Carbonell-Baeza et al. Fibromyalgia is a chronic pain syndrome characterized by an increased sensitivity to painful stimuli (hyperalgesia) and lowered pain threshold (allodynia) (Mork, Vasseljen, & Nilsen, 2010). In addition to pain and associated symptoms (fatigue, sleep disturbances, stiffness, cognitive difficulty, and mood disturbances) (Bennett, Jones, Turk, Russell, & Matallana, 2007; Wolfe et al., 1990), activity limitations and functional impairment are common in fibromyalgia (Jones, Rutledge, Jones, Matallana, & Rooks, 2008; Mannerkorpi, Svantesson, & Broberg, 2006). The 6-minute walk test (6-MWT) is commonly used to assess functional capacity in pathologic conditions, such as cardiopulmonary diseases (Demers, McKelvie, Negassa, & Yusuf, 2001; Guazzi, Dickstein, Vicenzi, & Arena, 2009; Rasekaba, Lee, Naughton, Williams, & Holland, 2009), Alzheimer disease (Ries, Echternach, Nof, & Gagnon Blodgett, 2009), obesity (Beriault et al., 2009), and fibromyalgia (Carbonell- Baeza, Aparicio, Martins-Pereira, et al., 2010; Carbonell-Baeza, Aparicio, Ortega, et al., 2010; King et al., 1999; Mannerkorpi et al., 2006; Pankoff, Overend, Lucy, & White, 2000). The 6-MWT has been widely used in research with fibromyalgia patients, with a focus on the walking distance parameters rather than the physiologic parameters of this submaximal exercise test (Astin et al., 2003; Gowans, Dehueck, Voss, Silaj, & Abbey, 2004; Mannerkorpi, Ahlmen, & Ekdahl, 2002; Mannerkorpi, Nordeman, Ericsson, & Arndorw, 2009; Rooks et al., 2007; Rooks, Silverman, & Kantrowitz, 2002). It has been reported that the distance walked during the 6-MWT is lower in female fibromyalgia patients than in healthy women (Jones, Rutledge, & Aquino, 2010; Mannerkorpi, Burckhardt, & Bjelle, 1994). However, it is not well known how the 6-MWT correlates with tenderness, quality of life, coping strategies, and symptomatology in fibromyalgia patients. King et al. (1999) and Pankoff et al. (2000) found an association between the distance walked in the 6-MWT and the Fibromyalgia Impact Questionnaire score (FIQ) in patients with fibromyalgia. Mannerkorpi et al. (2006) found an association between the 6-MWT and the subscales physical impairment and pain of FIQ and the subscale of physical function and bodily pain of the Short-Form Health Survey 36 (SF-36), but no information was provided regarding the association of the 6-MWT with the rest of subscales of either FIQ and SF-36. Ayan et al. (2007) only observed association with the subscale physical impairment of FIQ and not with the rest of subscales or the total score of FIQ. It has been suggested that the 6-MWT could be used as a complementary tool in the armamentarium used in the clinical examination when planning treatment for patients with fibromyalgia (Mannerkorpi et al., 2006). However, whether the 6-MWT can be used as an indicator of fibromyalgia symptomatology and quality of life remains to be investigated. Likewise, studies investigating the association between the distance walked in 6-MWT with tenderness or coping strategies are scarce. The purpose of the present study was to examine the relationship of the 6-MWT with tenderness, symptomatology, quality of life, and coping strategies in women with fibromyalgia. To better understand these relationships is of clinical and public health interest. METHODS Participants A total of 118 women with fibromyalgia were included in this study. Patients were recruited from a local association of fibromyalgia patients from Granada (Spain). The inclusion criterion was meeting the American College of Rheumatology criteria: widespread pain for >3 months and pain with 4 kg/cm of pressure reported for $11 of 18 tender points (Wolfe et al., 1990). All of the participants gave her written informed consent after receiving detailed information about the aims and study procedures. The study was approved by the Ethics Committee of the Hospital Virgen de las Nieves (Granada, Spain). The participants were (mean SD) years old. The mean body mass index was kg/m 2. Fifty-three percent were diagnosed #5 years earlier, and 47% were diagnosed>5 years earlier. Seventy-one percent were postmenopausal. The majority of the participants were married (75%). Sixty-one percent were employed at home (housewife), 23% working, 7% retired, 6% unemployed, and 2% students. Measurements 6-MWT. This test consists of determining the maximum distance (in meters) that can be walked in 6 minutes along a 45.7-meter rectangular course (Rikli & Jones, 1999). In earlier studies, 6-MWT demonstrated satisfactory reliability in fibromyalgia (King et al., 1999; Mannerkorpi, Svantesson, Carlsson, & Ekdahl, 1999; Pankoff et al., 2000). The rate of perceived exertion was assessed after the test using the Borg scale (6-20) (Borg, 1982). Tenderness. The 18 tender points according to the American College of Rheumatology criteria for classification of fibromyalgia were assessed using a standard pressure algometer (FPK 20; Effegi, Alfonsine, Italy) (Wolfe et al., 1990). The pressure algometer was applied to each tender point, perpendicular to the tissue, and patients were asked to say stop the moment pressure

3 6-Minute Walk Test in Fibromyalgia 3 became painful. The pressure value was registered, and the mean of two successive measurements at each tender point was used for the analysis. Tender point was scored as positive when the patient noted pain at a pressure of #4 kg/cm 2. The total count of such positive tender points was recorded for each participant. The algometer score was calculated as the sum of the pain-pressure values obtained for each tender point. FIQ. The FIQ is a self-administered questionnaire designed to assess the components of health status that are believed to be most affected by fibromyalgia and has been validated for Spanish populations with fibromyalgia (Rivera & Gonzalez, 2004). This questionnaire is composed of three subscales rated on Likert-type scale and seven subscales rated on a visual analog scale. All of the subscales range from 0 to 10, where high scores indicate a higher negative impact and/or a greater severity of symptoms. A total score may be obtained after normalization of some subscales and summing the subscales. The FIQ total score range from 0 to 100, and a higher score indicates a greater impact of the syndrome (Rivera & Gonzalez, 2004). The total score of FIQ and the subscales for physical function, feel good, pain, fatigue, morning tiredness, stiffness, anxiety, and depression were used in the study. SF-36. This is a generic instrument assessing healthrelated quality of life and has been validated for Spanish populations (Alonso, Prieto, & Anto, 1995). It contains 36 items grouped into eight subscales ranging from 0 to 100, where higher scores indicate better health: physical functioning, physical role, bodily pain, general health, vitality, social functioning, emotional role, and mental health. Vanderbilt Pain Management Inventory. The Vanderbilt Pain Management Inventory (VPMI) (Brown & Nicassio, 1987) adapted as a Spanish version (Esteve, Lopez, & Ramirez-Maestre, 1999) was used to assess coping strategies. The scale has 18 items divided into two subscales designed to assess how often chronic pain sufferers use active and passive coping. The frequency with which patients use each strategy when their pain reaches a moderate or greater level of intensity is rated on a 5-point scale. Seven of the item scores are summed to create the active coping scale score, and the remaining 11 items are summed to create the passive coping score. Active coping is when patients attempt to function despite their pain, and passive coping is when patients relinquish control of their pain to others or allow other areas of their life to be adversely affected by pain. Statistical Analyses The relationship of the 6-MWT with tenderness, quality of life, coping strategies, and symptomatology was analyzed with the Spearman correlation coefficient. A correlation from 0 to 0.25 indicates an absent or weak relationship, a correlation from 0.25 to 0.50 a fair relationship, a correlation from 0.50 to 0.75 a moderate to good relationship, and a correlation >0.75 a very good relationship (Colton, 1974; Mannerkorpi et al., 2006). Statistical analysis was conducted using the Predictive Analytics Software (SPSS v for Windows; Chicago, IL, USA), and significance level was 5%. RESULTS Table 1 shows the medians and lower and upper quartiles of the study variables in women with fibromyalgia. The 6-MWT showed a weak relationship with tenderness (r and for algometer score and tender points count, respectively; both p <.05; Table 2). Likewise, the relationship between the 6-MWT and global score of FIQ and FIQ subscales of pain and fatigue were weak (r 0.201, 0.211, and 0.226, respectively; all p <.05; Table 2). A fair relationship between the 6-MWT and physical impairment subscale of FIQ (r 0.365; p<.001) was noted (Table 2). Table 3 shows the relationship of the 6-MWT with SF-36 and VPMI in women with fibromyalgia. The 6-MWT showed a weak relationship with bodily pain and vitality scales of SF-36 (r and 0.258, respectively; both p ¼.005), and a fair relationship with physical function (r 0.347; p<.001). The 6-MWT showed a weak relationship with passive coping (r 0.255; p ¼.006) and active coping of VPMI (r 0.223; p ¼.016). DISCUSSION The present study in women with fibromyalgia shows significant relationships, ranging from weak to fair, of the 6-MWT with tenderness, symptomatology, quality of life, and coping strategies in women with fibromyalgia. These findings indicate that functional capacity, as assessed by the distance walked in 6 minutes, might be important when planning the assessment, treatment, and monitoring of patients with fibromyalgia. Regular physical activity is known to enhance functional capacity in fibromyalgia patients and is recommended for the management of fibromyalgia (Brosseau et al., 2008a, 2008b; Busch, Barber, Overend, Peloso, & Schachter, 2007; Jones, Adams, Winters-Stone, & Burckhardt, 2006; Kelley, Kelley, Hootman, & Jones, 2010). To adequately prescribe individualized exercise programs (type, duration, intensity, and frequency), it is important to know the patient s functional capacity levels as well as to understand the potential

4 4 Carbonell-Baeza et al. TABLE 1. Descriptive Characteristics of the Study Sample n Median 25th percentile 75th percentile 6-min distance walked RPE Pressure pain Algometer score Tender point counts FIQ Global score Physical impairment Feel good Pain Fatigue Rested Stiffness Anxiety Depression SF-36 Physical function Physical role Bodily pain General health Vitality Social function Emotional role Mental health VPMI Passive coping Active coping FIQ ¼ Fibromyalgia Impact Questionnaire; RPE ¼ rate of perceived exertion; SF-36 ¼ Short-Form Health Survey 36; VPMI ¼ Vanderbilt Pain Management Inventory. TABLE 2. Relationship of 6-Minute Walking Distance With Tenderness and Symptomatology (Fibromyalgia Impact Questionnaire [FIQ]) in Women With Fibromyalgia Outcome n r p Value Tenderness Algometer score Tender point count FIQ Global score Physical impairment <.001 Feel good Pain Fatigue Rested Stiffness Anxiety Depression implications that enhancing fitness may have of patient s overall health. The strongest associations were observed between the 6-MWT and the subscales of physical impairment (FIQ) and physical function (SF-36), which suggests that patients able to walk a longer distance also have a better perceived physical functional capacity. Of note is that both physical impairment (measured by FIQ) and physical function (measured by SF-36) scales include items related to the capacity of walking, which may explain the stronger relationships found compared with the other scales. A weak inverse association between the 6-MWT and the total score of FIQ was noted, as well as with the subscales of FIQ pain and fatigue, indicating that the greater the distance walked, the lower the score in FIQ, pain, and fatigue. A positive association between the 6-MWT and the subscales of SF-36 bodily pain, vitality, and mental health were also observed. Patients with higher performance in the walk test reported better scores in the subscales bodily pain, vitality, and mental health. Overall, fibromyalgia patients with higher performance in 6-MWT present

5 6-Minute Walk Test in Fibromyalgia 5 TABLE 3. Relationship of 6-Minute Walking Distance With Quality of Life (Short-Form Health Survey 36 [SF-36]) and Coping Strategies (Vanderbilt Pain Management Inventory [VPMI]) in Women With Fibromyalgia Outcome n r p Value SF-36 Physical function <.001 Physical role Bodily pain General health Vitality Social function Emotional role Mental health VPMI Passive coping Active coping lower tenderness, perceived pain, and fatigue, more vitality and perceived functional capacity, and better mental health than those patients with lower performance. These findings are in agreement with other studies. Mannerkorpi et al. (2006) found a fair correlation between the 6-MWT and physical impairment (FIQ) and physical function (SF-36) (n ¼ 69; r 0.48 and 0.49, respectively; both p<.001) and a weak association with the pain subscale of FIQ and bodily pain of SF-36 (r 0.39 and 0.38, respectively; both p<.01). King et al. (1999) showed an association between the 6-MWTand total score of FIQ (n ¼ 96;r 0.325). In contrast, Ayan et al. (2007) (n ¼ 29) found correlation only between the 6-MWT and physical impairment and not with the total score of FIQ or other subscale. A weak association between the 6-MWT and tenderness was noted. A positive association between the 6-MWT and algometer score indicates that the greater the distance walked, the higher the pain threshold values obtained for each tender point measured. In contrast, the inverse association observed between the 6-MWT and tender point counts indicates that the greater the distance walked, the lower the number of tender points that scored positive when the patient noted pain at a pressure of #4 kg/cm 2. Overall, associations between the 6-MWT and the four pain-related variables (algometer score, tender points count, subscale of FIQ pain, and subscale of SF-36 bodily pain) were observed. In agreement with Mannerkorpi et al. (2006) and despite pain being the main symptom in fibromyalgia, the correlation coefficient values between the performance in the 6-MWT and pain tended to be lower than those between the 6-MWT and physical function or activity limitations. Nevertheless, these findings are of relevance and informative. It was reported that increases in physical impairments (reduced functional capacity) and problems with performing functional tasks of daily living reduce patients quality of life as well as increase the risk of falls and disability (Jones, Rutledge, & Aquino, 2010). The present study shows that patients who walked greater distances reported higher use of active coping and lower use of passive coping strategies. In agreement with these results, several studies showed that higher levels of passive coping are associated with lower levels of functioning and higher levels of pain intensity in chronic pain patients (Ramirez-Maestre, Esteve, & Lopez, 2008; Snow-Turek, Norris, & Tan, 1996). However, patients with higher use of active coping reported higher levels of daily functioning (Ramirez-Maestre et al., 2008; Snow-Turek et al., 1996). Of note is that our results concur with earlier studies despite the present study using an objective measure of functional capacity (the 6-MWT) whereas others used questionnaires. Owing to the study design (i.e., cross-sectional), it was not possible to establish the direction of the associations. Future intervention studies should determine the potential effect of increasing the functional capacity on the overall health status of the patients. Another limitation of this study is that owing to logistic reasons the participants were not familiar with the 6-MWT, and a positive effect of learning has been reported in earlier studies (Pankoff et al., 2000; Wu, Sanderson, & Bittner, 2003). Of note is that the assessment of this test requires minimal instrumentation and time, and therefore the assessment of this variable is clinically feasible. In summary, a weak to fair associations of the 6-MWT with tenderness, symptomatology, quality of life, and coping strategies in women with fibromyalgia were observed. These findings, together with those from earlier research (Mannerkorpi et al., 2006), support the use of the 6-MWT as an additional tool when planning the assessment, treatment, and monitoring of patients with fibromyalgia. Acknowledgments The authors thank the researchers for the CTS-545 research group. They gratefully acknowledge all participating patients for their collaboration.

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