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Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

Objective

To evaluate the impact of acute gout on foot pain, impairment, and disability.

Methods

This prospective observational study recruited 20 patients with acute gout flares. Patients were recruited from emergency departments, hospital wards, and rheumatology outpatient clinics throughout Auckland, New Zealand. Patients were recruited at the time of the flare (baseline visit) and then reassessed at a followup visit once the acute flare had resolved 6–8 weeks after the initial assessment. Swollen and tender joint counts, C-reactive protein levels, and serum urate levels were recorded at both visits. General and foot-specific outcome measures were also recorded at each visit, including pain visual analog scale, Health Assessment Questionnaire II, Lower Limb Tasks Questionnaire, and Leeds Foot Impact Scale.

Results

The foot was affected by acute gout in 17 patients (85%). Objective measures of joint inflammation, including swollen and tender joint counts and C-reactive protein levels, significantly improved at the followup visit compared with the baseline visit. At baseline, high levels of foot pain, impairment, and disability were reported. All patient-reported outcome measures of general and foot-specific musculoskeletal function improved at the followup visit compared with the baseline visit. However, pain, impairment, and disability scores did not entirely normalize after resolution of the acute gout flare.

Conclusion

Patients with acute gout flares experience severe foot pain, impairment, and disability. These data provide further support for improved management of gout to prevent the consequences of poorly controlled disease.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

Gout is the most common inflammatory arthritis affecting men (1), and gout typically presents as acute self-limiting attacks of severe joint inflammation. The prevalence of gout in the US has risen over the last 20 years and now affects 8.3 million American adults (3.9%) (2). In New Zealand, rates of gout have also increased (3), with most recent prevalence estimates of 3.2% for European adults, 6.1% for Maori adults, and 7.6% for Pacific Islander adults (4).

The foot is frequently affected by acute gout flares, most often at the first metatarsophalangeal (MTP) joint, midfoot, and ankle joint (5–8). In a cross-sectional survey of 354 patients with gout, 76% had involvement of the first MTP joint (5). Roddy et al (8) reported that acute gout affected the first MTP joint in 66% of patients, the midfoot in 20% of patients, and the ankle in 15% of patients.

Although research has shown that gout is associated with musculoskeletal disability, work disability, and reduced health-related quality of life (9–12), the specific impact of gout flares on musculoskeletal function and disability has not been explored in detail. Moreover, although it has been well recognized that gout frequently affects the feet, the consequences of acute gout on the feet have not been described. At present, no existing guidelines address specific management of foot disease in gout. The aim of this study was to understand the impact of acute gout flares on foot pain, impairment, and disability.

Significance & Innovations

  • Patients with acute gout flares experience severe foot pain, impairment, and disability.

  • There is a high predilection of gout to affect the foot.

  • The disease burden of gout on the foot is substantial.

PATIENTS AND METHODS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

This study was a longitudinal observational study designed to assess the impact of acute gout on the foot. Patients were recruited from emergency departments, hospital wards, and rheumatology outpatient clinics throughout Auckland, New Zealand. Patients were recruited at the time of the flare (baseline visit) and then reassessed at a followup visit once the acute flare had resolved 6–8 weeks after the initial assessment. The Northern X Regional Ethics Committee approved the study, and all patients provided written informed consent.

Patients were included if they had an acute gout attack within the previous 48 hours. The diagnosis of acute gout was made according to the American College of Rheumatology preliminary criteria for the classification of the acute arthritis of primary gout (13). Patients were assessed on 2 separate occasions by a single examiner (MF). At the baseline visit, the following clinical information was recorded: age, sex, ethnicity, medical history, and medications. The clinical information specific to the patient's gout and their current flare was recorded. Weight, height, and subcutaneous tophus count were also recorded. At each visit, the following measures were recorded: tender joint count, swollen joint count, C-reactive protein level, serum urate level, patient global assessment (100-mm visual analog scale [VAS]), pain (100-mm VAS), Health Assessment Questionnaire II (HAQ-II) (14, 15), and a detailed assessment of foot structure, function, and disability, using the measures outlined below.

Foot pain was evaluated using a pain VAS. Pain intensity was scored along a 100-mm horizontal line with the left-most boundary representing no pain and the right-most boundary representing extreme pain. Higher scores indicated greater pain.

Forefoot and rearfoot deformities were quantified using the Structural Index score (16), which considered hallux valgus, MTP joint subluxation, fifth MTP joint exostosis, and claw/hammer toe deformities for the forefoot (range 0–12) and calcaneus valgus/varus angle, ankle range of motion, and pes planus/cavus deformities for the rearfoot (range 0–7). Foot type was assessed using the Foot Posture Index, which is a validated method for quantifying standing foot posture, such as flat or high-arched feet (17). The normal adult population mean Foot Posture Index score is +4, and scores above +4 suggest a pronated (flat foot) type.

Foot impairment and disability were measured using the Leeds Foot Impact Scale (LFIS) (18). This is a self-completed questionnaire that was developed to evaluate foot health status in patients with rheumatoid arthritis. The LFIS comprises 51 questions divided into 2 subcategories: impairment/footwear (LFISIF) and activity limitation/participation restriction (LFISAP). These 2 components relate closely to the domains outlined by the World Health Organization (WHO) International Classification of Functioning, Disability and Health (ICF) (19). The LFIS also measures the psychological effects of the disease on the individual. Each question is answered as being true or false, with a true response scored as 1 point and a false response as 0. Scores are then totaled to provide an overall score for each subsection, with a maximum overall score of 51. Higher scores are indicative of greater levels of disability. Turner et al (20) reported that an LFISIF score of >7 points is indicative of moderate-to-high levels of foot impairment and an LFISAP score of >10 points is indicative of moderate-to-high levels of foot disability.

The Lower Limb Tasks Questionnaire was used to measure function in the lower extremity (21). This questionnaire captures the patient's account of their functional status within the previous 48 hours and is divided into 2 domains: activities of daily living and recreational activities.

All data were analyzed using SPSS V18.0 for Windows. Scores between the baseline and followup visits were analyzed using dependent t-tests for paired samples. Categorical data were analyzed using chi-square tests. All tests were 2-tailed and P values less than 0.05 were considered significant.

RESULTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

Twenty patients were recruited into the study and completed the baseline visit (Figure 1). Followup data were available for 18 patients (90%). The mean ± SD time between visits was 74 ± 42 days. One patient withdrew at followup due to non–gout-related illness and another patient could not be contacted for followup.

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Figure 1. Flow of study patients.

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The clinical characteristics at baseline are shown in Table 1. Patients were predominantly middle-aged Maori and Pacific Islander men, with high rates of obesity and comorbidities such as hypertension and cardiovascular disease. These patients reported high frequency of gout flares (approximately 1 per month). Allopurinol use was low in the group overall. Most of the patients reported that their first flare had affected the foot, most often the first MTP joint.

Table 1. Baseline clinical data (n = 20)*
  • *

    Values are the number (percentage) unless otherwise indicated.

Male sex17 (85)
Age, mean ± SD years54 ± 16
Ethnicity 
 New Zealand European7 (35)
 New Zealand Maori6 (30)
 Pacific Islander7 (35)
Comorbidities 
 Hypertension13 (65)
 Cardiovascular disease10 (50)
 Diabetes mellitus2 (10)
Duration of gout, mean ± SD years13.2 ± 11.4
Diuretic use5 (25)
Aspirate proven disease12 (60)
Site of first flare 
 First metatarsophalangeal joint12 (60)
 Midfoot1 (5)
 Ankle6 (30)
 Knee0 (0)
 Elbow0 (0)
 Hands1 (5)
Body mass index, mean ± SD kg/m235 ± 11
Any tophi9 (45)
No. of total subcutaneous tophi, mean ± SD1.9 ± 2.8
No. of subcutaneous tophi affecting feet, mean ± SD0.3 ± 0.6
No. of flares in previous 3 months, mean ± SD3.4 ± 2.7

The clinical features of the gout flares at the baseline and followup visits are shown in Table 2. The foot, in particular the first MTP joint and the ankle joint, was affected in 17 patients (85%) at the baseline visit. Polyarticular flares were common. High scores for pain and disability were observed at the baseline visit. There was a significant improvement in clinical measures of acute gout between the baseline and followup visits in patient global assessment, HAQ-II scores, swollen joint count, tender joint count, and C-reactive protein level. Serum urate level did not significantly change between the 2 visits. All patients were receiving treatment for management of acute gout at the baseline visit, most often nonsteroidal antiinflammatory drugs (NSAIDs). NSAID use was significantly less frequent at the followup visit.

Table 2. Clinical features of gout flares*
VariableBaseline visit (n = 20)Followup visit (n = 18)P
  • *

    Values are the number (percentage) unless otherwise indicated. NA = not applicable; MTP = metatarsophalangeal; HAQ-II = Health Assessment Questionnaire II; NSAID = nonsteroidal antiinflammatory drug.

Site of flare NANA
 First MTP joint6 (30)  
 Midfoot1 (5)  
 Ankle10 (50)  
 Knee3 (15)  
 Elbow2 (10)  
 Hands3 (15)  
Polyarticular flare9 (45)NANA
Tender joint count, mean ± SD8 ± 91 ± 10.01
Swollen joint count, mean ± SD3 ± 30 ± 1< 0.001
Patient global assessment score, mean ± SD65 ± 2332 ± 23< 0.001
HAQ-II, mean ± SD1.9 ± 0.60.9 ± 0.6< 0.001
C-reactive protein level, mean ± SD mg/liter54.8 ± 61.63.2 ± 1.40.03
Serum urate, mean ± SD mmoles/liter0.50 ± 0.150.42 ± 0.120.65
Allopurinol use8 (40)11 (61)0.06
Colchicine use13 (65)9 (50)0.13
Prednisone use10 (50)5 (28)0.11
NSAID use16 (80)5 (28)< 0.001

The foot-specific measures at the baseline and followup visits are shown in Table 3. Foot pain, as measured by the foot pain VAS, was high at the time of the gout flare and reduced by 73% at followup. Foot Posture Index scores did not differ between baseline and followup visits. At both visits, the Foot Posture Index scores indicated a pronated (flat foot) foot type. The Structural Index score for the forefoot and rearfoot also did not differ between the 2 visits. Both the forefoot and rearfoot structural indices demonstrated moderate structural problems.

Table 3. Foot-specific measures of pain, impairment, and disability
VariableBaseline, mean ± SDFollowup, mean ± SDP
Foot pain visual analog scale60 ± 2816 ± 16< 0.001
Structural Index (forefoot)5 ± 55 ± 51.00
Structural Index (rearfoot)6 ± 35 ± 30.25
Foot Posture Index5 ± 36 ± 30.13
Leeds Foot Impact Scale (impairment)16 ± 49 ± 5< 0.001
Leeds Foot Impact Scale (activity/participation)25 ± 518 ± 80.002
Lower Limb Tasks Questionnaire (activity)16 ± 728 ± 7< 0.001
Lower Limb Tasks Questionnaire (recreational)4 ± 312 ± 8< 0.001

There were significant differences between baseline and followup visits in both components of the LFIS (LFISIF and LFISAP) (Table 3). High levels of impairment (scores >7 points on the LFISIF) were found with all 20 patients (100%) at baseline and 10 patients (54%) at the followup visit (baseline versus followup visit, P < 0.001). High levels of disability (scores >10 points on the LFISAP) were also found with all 20 patients (100%) at baseline and 7 patients (35%) reporting severe disability at the followup visit (baseline versus followup visit, P < 0.001).

Baseline data for both domains of the Lower Limb Tasks Questionnaire indicated severe restrictions of daily living and recreational activities (Table 3). These values improved at the followup visit but did not entirely normalize.

DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

This study shows that acute gout flares are associated with severe foot pain, impairment, and disability. Measures of foot pain, impairment, and disability improved following treatment of the acute gout attack, but did not entirely normalize. Most patients in our study reported that their initial gout attack affected the foot, and over two-thirds had a documented flare affecting the foot at the baseline visit. These findings emphasize the predilection of gout to affect the foot, and provide support to prevent recurrent flares and the consequences of gout flares on musculoskeletal function.

Clinical measures of gout flares, such as swollen and tender joint counts, patient global assessment, HAQ-II scores, and C-reactive protein levels, were all high at the time of the baseline visit, with significant improvements following resolution of the flare. In contrast, there was no change in the serum urate level between the 2 time points. Previous studies have reported that serum urate level frequently drops at the time of an acute gout flare, and rises in the convalescent period (22–24). It is possible that the trend to greater use of allopurinol at the followup visit has masked this effect in our study.

The severity of foot pain at the time of the gout flare was consistent with reports of generalized pain from clinical trials of acute gout (25, 26). We observed that at the followup visit, pain did not entirely resolve, suggesting that foot-related pain may be a constant feature in patients with recurrent gout flares. This depiction of pain has been reported in a quantitative study where patients with severe gout described living with constant pain (27). We also found that patients with an acute flare experienced high levels of general and foot-related impairment and disability as measured by the LFIS. Moreover, at the followup visit, more than one-half of the patients still reported foot impairments and one-third reported ongoing disability. The current study was of a prospective observational design, and patients were recruited at the time of the acute gout flare. Therefore, assessment of prior foot function, impairment, and disability could not be undertaken. However, in a previous case–control study (28), we assessed subjective and objective measures of foot function in patients with a history of gout and in control subjects with no history of gout or other forms of arthritis. The gout cases were specifically excluded if they had an acute gout flare. The key findings of that study were that patients with a history of gout had higher levels of general and foot-specific disability, pain, and impairment compared with control participants. Collectively, our findings suggest that the disease burden of gout on the foot is substantial and has a negative impact on the well-being of the patient.

In contrast with the LFIS, which contains questions concerning pain, impairment, and quality of life, the Lower Limb Tasks Questionnaire provides data solely related to difficulty in activities of daily living and in recreational activities. In these domains, lower extremity function was appreciably reduced during an acute flare. Of particular note is that recreational activities were severely limited at the time of the flare, and at the followup visit, these activities remained restricted. These data indicate an important limitation in the ability of the individual to participate in exercise, which in turn may have an adverse impact on prevention of obesity and management of cardiovascular risk. These data are consistent with previous qualitative work, indicating that patients give up recreational activities such as sport because of gout (27). Difficulty in daily living activities improved to more satisfactory levels at followup; however, they remained well below normative values (38/40) for a much older cohort (69 years of age) without pathology (29). The activities of daily living score from the followup visit was similar to a study on knee osteoarthritis (29). Together, these data demonstrate that recurrent acute flares reduce the patient's lower extremity function severely.

The primary limitation of this study was its small sample size. Despite the small sample size, clear differences in foot parameters were observed across the baseline and followup visits. Another limitation was that recruitment was primarily from secondary care facilities/providers, and it is possible that acute gout flares treated within the primary care environment may have produced different levels of severity and impact. The majority of patients in this study were of Maori and Pacific Islander ancestry, with low rates of allopurinol use. This finding is consistent with our previous studies of poorly controlled gout in New Zealand (30, 31). The long disease duration and severity of chronic gout in the patients may explain the residual function limitation observed in the baseline visits. Analysis of the impact of gout flares from other units and in primary care will be of great interest.

This study raises a number of further research questions. We observed that the majority of patients had a pronated (flat foot) foot type. It is possible that abnormal biomechanical loading due to excessive pronation may contribute to the clinical manifestations of gout in the feet. Future prospective studies investigating the relationship between foot type and severity/persistence of disease will be of interest. Currently, there are no specific tools/indices that have been developed or validated in individuals with gout affecting the foot. Future work could be directed toward developing a foot-specific tool for gout for clinical practice and for use as an outcome measure in clinical trials of gout. In addition to patient-reported outcome measures, such a tool could include the presence of digital deformities, tophi, and range of motion at the first MTP, subtalar, and ankle joints. This may further lead to the development of a more tailored scoring system for foot impairment and disability in both acute and chronic gout in accordance with the WHO ICF model for disability (19). Furthermore, despite the frequent involvement of the foot in gout, no studies to date have examined the role of footwear in this condition. The relationship between foot pain, deformity, and footwear warrants further investigation, since this may provide useful insights into nonpharmacologic approaches to gout management.

In conclusion, the foot is frequently affected by acute gout flares. Patients with acute gout flares experience severe foot pain, impairment, and disability. These data provide further support for improved management of gout to prevent the consequences of poorly controlled disease.

AUTHOR CONTRIBUTIONS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

All authors were involved in drafting the article or revising it critically for important intellectual content, and all authors approved the final version to be published. Dr. Rome had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study conception and design. Rome, Frecklington, McNair, Gow, Dalbeth.

Acquisition of data. Rome, Frecklington, Dalbeth.

Analysis and interpretation of data. Rome, Frecklington, McNair, Gow, Dalbeth.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES