DFA 2000-625X Diabetic Foot & Ankle Vol. 2, No. 00, September 2011, pp. 1–6 sici xxx PUBMED Abbreviation Zameer Aziz MB ChB (Dundee)

*Aziz Nather Associate Professor and Senior ConsultantDepartment of Orthopaedic SurgeryNational University of Singapore and National University Hospital Singapore 119074 +(65) 67724323 Fax:(65) 67780720

Wong Keng Lin MBBS (Singapore) Aziz Nather FRCS (Ed)

*Aziz Nather Associate Professor and Senior ConsultantDepartment of Orthopaedic SurgeryNational University of Singapore and National University Hospital Singapore 119074 +(65) 67724323 Fax:(65) 67780720

Chan Yiong Huak PhD Department of Orthopaedic Surgery National University Health System

Singapore

Biostatistics Unit, Yong Loo Lin School of Medicine National University of Singapore

Singapore

Diabetic Foot & Ankle CLINICAL RESEARCH ARTICLE Predictive factors for lower extremity amputations The objective of this study was to evaluate the epidemiology of diabetic foot infections (DFIs) and its predictive factors for lower extremity amputations. A prospective study of 100 patients with DFIs treated at the National University Hospital of Singapore were recruited in the study during the period of January 2005–June 2005. A protocol was designed to document patient's demographics, type of DFI, presence of neuropathy and/or vasculopathy and its final outcome. Predictive factors for limb loss were determined using univariate and stepwise logistic regression analysis. The mean age of the study population was 59.8 years with a male to female ratio of about 1:1 and with a mean follow-up duration of about 24 months. All patients had type 2 diabetes mellitus. Common DFIs included abscess (32%), wet gangrene (29%), infected ulcers (19%), osteomyelitis (13%), necrotizing fasciitis (4%) and cellulitis (3%). Thirteen patients were treated conservatively, while surgical debridement or distal amputation was performed in 59 patients. Twenty-eight patients had major amputations (below or above knee) performed. Forty-eight percent had monomicrobial infections compared with 52% with polymicrobial infections. The most common pathogens found in all infections (both monomicrobial and polymicrobial) were Staphylococcus aureus (39.7%), Bacteroides fragilis (30.3%), Pseudomonas aeruginosa (26.0%) and Streptococcus agalactiae (21.0%). Significant univariate predictive factors for limb loss included age above 60 years, gangrene, ankle-brachial index (ABI) <0.8, monomicrobial infections, white blood cell (WBC) count ≥ 15.0×10⁹/L, erythrocyte sedimentation rate ≥100 mm/hr, C-reactive protein ≥15.0 mg/dL, hemoglobin (Hb) ≤10.0g/dL and creatinine ≥150 µmol/L. Upon stepwise logistic regression, only gangrene, ABI <0.8, WBC ≥ 15.0×10⁹/L and Hb ≤10.0g/dL were significant. gangrene diabetes mellitus amputation ulceration With a prevalence of 8.2% in 2004 1, diabetes is one of the leading causes of lower limb amputations in Singapore. Diabetes mellitus itself accounts for almost 700 amputations annually 2. Its devastating complications, including peripheral vascular disease and neuropathy, predispose patients to having diabetic foot infections (DFIs) that most commonly require urgent attention in order to avoid a lower extremity amputation 3. In the past two decades, publications from Singapore concerning diabetes mellitus underscored the alarming prevalence of its complications in the republic 4 5 6 . However, the only studies on DFI in Singapore were undertaken in the 1970s and 1980s 7 8 9 . These studies mainly concentrated on the pathophysiology of DFI, such as the defective function of the polymorphonuclear leukocytes and the benefits of maintaining optimal blood glucose levels, along with discussions on criteria for conservative versus ablative surgery. In Singapore, there had been no latest literature studying DFI and predictive factors for limb loss, which would provide an insight to better optimization of patients with DFIs. Our study is the most comprehensive study on DFI undertaken in Singapore recently. The aim of this study was to evaluate the epidemiology of DFI and to determine its parameters that could be predictive factors for limb loss resulting from major below and above the knee amputations (AKA). This is a prospective study of 100 patients diagnosed and treated with DFI in the National University Hospital of Singapore during the period of January 2005–June 2005. Medical and surgical treatment was provided by our multidisciplinary team approach for the treatment of the diabetic foot. Data on all patients were documented using a carefully designed study protocol. Ethics approval was sought prior to commencement of the study and informed consent was obtained from all subjects studied in this cohort. Documentation included patient demographics such as age, sex, race and type of DFI (abscess, wet gangrene, infected ulcers, osteomyelitis, necrotizing fasciitis and cellulitis). Objective clinical data such as clinical examination for fever, neuropathy and vasculopathy were also collected. Neuropathy was assessed using the 5.07 Semmes-Weinstein Monofilament Test (SWMT). Ability to detect seven or less sites out of a total of ten sites indicated the presence of peripheral neuropathy. The ankle-brachial index (ABI) measured was used to determine if a patient had vasculopathy. Patients with a recorded ABI value of <0.8 were considered to have vasculopathy. Laboratory investigations, including glycosylated hemoglobin (HbA1c), erythrocyte sedimentation rate (ESR), hemoglobin level (Hb), white blood cell (WBC) count, creatinine (Cr) and C-reactive protein (CRP) levels were recorded and documented. Blood cultures were performed for all patients and swabs were taken from the local infection sites for culture of aerobic and anaerobic organisms. In patients undergoing debridement or amputation, intra-operative infected tissue was examined for culture and sensitivities. The treatment administered to each patient was also recorded. Conservative treatment included, but was not limited to intravenous antibiotics, bedside wound debridement and local wound care, whereas surgical treatment included debridement or distal foot amputation versus major below the knee amputation (BKA) or AKA. Patients were considered to have a successful limb salvage procedure when they received conservative treatment only, or had undergone operations such as wound debridement, incision and drainage, and distal amputations such as toe disarticulation and ray amputation. Patients who had undergone major amputations (BKA or AKA) were classified as having a non-salvageable procedure performed. All patients were reviewed weekly or fortnightly for the first two months and subsequently monthly for a minimum of two years. In this cohort, the following factors were studied to see if they were significant predictive factors of limb loss: age, sex, ethnicity, type of DFI, fever, type of pathogen(s) encountered, presence of neuropathy and vasculopathy, WBC, ESR, CRP, Hb, HbA1c and Cr. All statistical analysis were performed using SPSS 14.0 with statistical significance set at (P< 0.050). Predictive factors for limb loss were determined using univariate and stepwise logistic regression analysis. The ages of our patients ranged between 21 and 91 years with a mean of 59.8 years. The majority were in their 5th and 6th decades of life (59.0%). Nineteen percent were in their 1st–4th decades of life, and the remaining 22.0% were in their 7th–9th decades of life. The ratio of male to female patients was approximately 1:1. Forty-nine percent of the patients were females and 51% were males. Racial distribution was 46% Chinese, 39% Malays and 15% Indians. In comparison with the national racial distribution of Singapore 10, which reported 75.6% Chinese, 13.6% Malays and 8.7% Indians, there was a significant increased representation in Malays (P< 0.001) and a significant decreased representation in Chinese (P< 0.001). All patients had type 2 diabetes mellitus for at least 5 years in duration. The most common DFIs were abscess (32%), wet gangrene (29%), infected ulcers (19%) and osteomyelitis (13%). Other infections included necrotizing fasciitis (4%) and cellulitis (3%). Culture swabs from ulcers or from infected tissues sent for bacterial cultures intra-operatively showed that 48% of the infections were monomicrobial and 52% were polymicrobial. For monomicrobial infections, the most common pathogens were Staphylococcus aureus (31.3%), methicillin-resistant S. aureus (MRSA) (16.7%) and Pseudomonas aeruginosa (16.7%). Other pathogens included Streptococcus agalactiae (12.5%), Bacteroides fragilis (12.5%), beta-haemolytic Streptococcus (4.1%), Peptostreptococcus (2.1%) and others (4.1%). For polymicrobial infections, the most common organisms found were S. aureus (48.1%), B. fragilis (46.2%) and P. aeruginosa (34.6%). Other pathogens included S. agalactiae (28.9%), Peptostreptococcus (19.2%), beta-haemolytic Streptococcus (15.4%), MRSA (13.5%) and others (13.5%). The commonest pathogens found in all infections (both monomicrobial and polymicrobial) were S. aureus (39.7%), B. fragilis (30.3%), P. aeruginosa (26.0%) and S. agalactiae (21.0%). Others included MRSA (15.0%), Peptostreptococcus (11.0%), beta-haemolytic Streptococcus (10.4%) and others (9.6%). Bose 11 and Frykberg 12 reported similar findings to our study. They found S. aureus to be the most common pathogen as in this study. With regards to the markers of infection, 62.0% had elevated WBC counts (WBC ≥ 11.0×10⁹), and 38.0% had WBC ≥ 15.0×10⁹/L. Ninety-seven percent had raised ESR (ESR ≥ 16mm/hr for males and ESR ≥ 19 mm/hr for females) and 53.0% had ESR ≥100 mm/hr. Ninety-five percent had elevated CRP (CRP ≥ 1.0 mg/dL) and 26.0% had CRP ≥ 15.0 mg/dL. Seventy-seven percent had reduced Hb levels (Hb ≤ 13.1 g/dL) and 31.0% had Hb ≤ 10.0 g/dL. Thirty-nine percent had elevated Cr levels (Cr ≥ 115 µmol/l) and 29.0% had Cr ≥ 150 µmol/l. The majority (79.0%) of the patients had poor control of diabetes, as indicated by their HbA1c level (> 7.0%). Fifteen percent of patients had HbA1c > 13.0%. Of the 100 patients documented, 37.0% experienced fever, 67.0% had ABI < 0.8 (indicating vasculopathy), and 84.0% were found to have sensory neuropathy based on SWMT. All patients had no prior surgical intervention performed for their DFI. The mean follow-up duration was 24 months. This was a single surgeon series, who dictated which procedure to perform and the surgical procedures were not staged. Thirteen patients were treated conservatively with intravenous antibiotics, bedside wound debridement and local wound care. Surgery was required in 87 patients, including 21 ray amputations, 18 debridements, 14 incisions and drainage, 6 toe disarticulations and 28 major amputations (24 BKA and 4 AKA). There were no re-infections or secondary surgical procedures required for patients who underwent surgery. The amputation rate of 28% is much lower than the higher amputation rate of 40% reported by Bose 7. Thirty-eight percent of patients older than age 60 suffered limb loss in comparison to 18.0% of patients younger than age 60 y. Patients older than age 60 were found to be a significant predictive factor for limb loss (P= 0.026), similar to findings by Leung et al. 13 and Santos et al. 14. Limb Loss Unadjusted Stepwise analysis Risk Factor Positive Negative OR (95% CI) P value OR (95% CI) P value Age >60 years 19 (38.0) 31 (62.0) 2.8 (1.1 – 7.0) 0.029 ≤ 60 years 9 (18.0) 41 (82.0) 1.0 Gender Male 12 (23.5) 39 (76.5) 0.6 (0.3– 1.5) 0.310 Female 16 (32.7) 33 (67.3) 1.0 Ethnicity Chinese 16 (34.8) 30 (65.2) 2.1 (0.8 – 5.5) 0.149 Malay 8 (20.5) 31 (79.5) 1.0 Indian 4 (26.7) 11 (73.3) 1.4 (0.4 – 5.6) 0.627 Type of DFI Abscess Yes 2 (6.3) 30 (93.8) 0.1 (0.0 – 0.5) 0.001 No 26 (38.2) 42 (61.8) 1.0 Gangrene Yes 17 (58.6) 12 (41.4) 7.7 (2.9 – 20.6) < 0.001 5.6 (1.7 – 18.7) 0.005 No 11 (15.5) 60 (84.5) 1.0 Infected Ulcer Yes 5 (26.3) 14 (73.7) 0.9 (0.3 – 2.8) 0.856 No 23 (28.4) 58 (71.6) 1.0 Osteomyelitis Yes 2 (15.4) 11 (84.6) 0.4 (0.1 – 2.1) 0.342 No 26 (29.9) 61 (70.1) 1.0 Necrotising Fasciitis Yes 2 (50.0) 2 (50.0) 2.7 (0.4 – 20.1) 0.312 No 26 (27.1) 70 (72.9) 1.0 Cellulitis Yes 0 (0.0) 30(100.0) NA 0.557 No 28 (38.2) 42 (61.8) 1.0 0.001 Complications Fever Yes 12 (32.4) 25 (67.6) 1.4 (0.6 – 3.4) 0.449 No 16 (25.4) 47 (74.6) 1.0 ABI < 0.8 Yes 26 (38.8) 41 (61.2) 9.8 (2.2 – 44.6) 0.001 19.9 (2.8-139.6) 0.003 No 2 (6.1) 31 (93.9) 1.0 Neuropathy Yes 25 (29.8) 59 (70.2) 1.8 (0.5 – 7.0) 0.546 No 3 (18.8) 13 (81.2) 1.0 Type of Pathogens Staphylococcus aureus Yes 9 (22.5) 31 (77.5) 0.6 (0.3 – 1.6) 0.317 No 19 (31.7) 41 (68.3) 1.0 Bacteriodes fragilis Yes 8 (26.7) 22 (73.3) 0.9 (0.4 – 2.4) 0.846 No 20 (28.6) 50 (71.4) 1.0 Pseudomonas aeruginosa Yes 10 (38.5) 16 (61.5) 1.9 (0.8 – 5.0) 0.167 No 18 (24.3) 56 (75.7) 1.0 Streptococcus agalactiae Group B Yes 2 (9.5) 19 (90.5) 0.2 (0.1 – 1.0) 0.034 No 26 (32.9) 53 (67.1) 1.0 MRSA Yes 7 (46.7) 8 (53.3) 2.7 (0.9 – 8.2) 0.117 No 21 (24.7) 64 (75.3) 1.0 Peptostreptococcus Yes 2 (18.2) 9 (81.8) 0.5 (0.1 – 2.7) 0.723 No 26 (29.2) 63 (70.8) 1.0 Beta- Haemolytic Streptococcus sp. Yes 1 (10.0) 9 (90.0) 0.3 (0.0 – 2.1) 0.275 No 27 (30.0) 63 (70.0) 1.0 Monomicrobial Yes 18 (37.5) 30 (62.5) 2.5 (1.0 – 6.2) 0.042 No 10 (19.2) 42 (80.8) 1.0 Polymicrobial Yes 10 (19.2) 42 (80.8) 0.4 (0.2 – 1.0) 0.042 0.2 (0.1 – 0.7) 0.010 No 18 (37.5) 30 (62.5) 1.0 Markers of Infection WBC ≥ 15.0 x 10⁹/L Yes 16 (42.1) 22 (57.9) 3.0 (1.2 – 7.5) 0.014 4.7 (1.3 – 16.8) 0.016 No 12 (19.4) 50 (80.6) 1.0 ESR ≥ 100 mm/hr Yes 22 (41.5) 31 (58.5) 4.8 (1.7 – 7.5) 0.001 No 6 (12.8) 41 (87.2) 1.0 CRP ≥ 15.0 mg/Dl Yes 12 (46.2) 14 (53.8) 3.1 (1.2 – 8.0) 0.017 No 16 (21.6) 58 (78.4) 1.0 Hb ≤ 10.0 g/dL Yes 16 (51.6) 15 (48.4) 5.1 (2.0 – 13.0) < 0.001 5.2 (1.5 – 17.7) 0.008 No 12 (17.4) 57 (82.6) 1.0 HbA1C > 7.0% Yes 19 (24.1) 60 (75.9) 2.4 (0.9 – 6.5) 0.093 No 9 (42.9) 12 (57.1) 1.0 Cr ≥ 150 µmol/l Yes 15 (51.7) 14 (48.3) 4.8 (1.9 – 12.3) 0.001 No 13 (18.3) 58 (81.7) 1.0 Gender was not found to be an important predictive factor for limb loss (P= 0.310). This is similar to findings by Miyajima et al. 15 and Gurlek et al. 16, although Hamalainen et al 17 showed otherwise, indicating that the male gender has a higher risk of undergoing lower extremity amputations. Ethnicity was also not a predictive factor for limb loss (P> 0.050) for all three major races in Singapore. This is in contrast to studies conducted in the United States, where Resnick et al. 18 showed that people of African American descent with diabetes have a much higher amputation risk than whites, as well as studies conducted in the United Kingdom, which showed that African Caribbean men had a lower risk of amputation than European men 19. In a recent study carried out on a larger cohort of 234 patients, Nather et al., however, have recently reported that the Malay ethnicity, along with a low-level of education and low average household income, were found to have a significantly higher incidence of diabetic foot problems 20. Among the types of DFI present, only gangrene was found to be highly significant as a predictive factor for limb loss (P< 0.001). Approximately 58.6% of cases involving wet gangrene had major amputations. Pittet et al. 21 also reported a similar finding, although their study showed that in addition to gangrene, plantar ulcers, deep tissue infections and osteomyelitis were also highly significant as predictive factors for limb loss. The significance of gangrene as a predictive factor for limb loss and the lack of significance for other types of DFI indicated urgency to actively treat infections with gangrene. Out of 37 patients presented with fever (temperature ≥ 38°C), twelve had major lower extremity amputations (32.4%). Fever was not found to be a predictive factor for limb loss (P= 0.449). Approximately 29.8% of patients with sensory neuropathy had a major amputation in comparison with 18.8% of those without neuropathy who had a major amputation. Neuropathy was not found to be a significant factor in predicting limb loss (P= 0. 546). As neuropathy is commonly regarded as a major factor that predisposes diabetic patients to lower extremity amputations, as shown by Reiber et al. 22 and Hamalainen et al. 17, it was surprising that neuropathy was not found to be significant in our study. About 38.8% of patients with ABI <0.8 (indicating vasculopathy) underwent major amputations, in comparison with 6.1% of patients with ABI ≥ 0.8 who had major amputations performed. The ABI <0.8 was found to be highly significant in predicting limb loss (P= 0.001), similar to findings by Pittet et al. 21 and Hamalainen et al. 17. Medial arterial calcinosis (MAC) occurs frequently and unpredictably in diabetic patients, and this may result in non-compressible arteries and artificially elevated ABI. Mayfield et al. 23 found that MAC is associated with an increased risk of ulceration, amputation and mortality. Hence, one should not be re-assured by a normal ABI in diabetic foot disease. Approximately 37.5% of patients with monomicrobial infections suffered from limb loss, in contrast to 19.2% of patients with polymicrobial infections. Comparison of monomicrobial versus polymicrobial infections as a predictive factor for limb loss showed that the former was significant (P= 0.042). Frykberg 12 reported in a review that severe infections are characterized by polymicrobial involvement, but our findings showed monomicrobial infections to be significant as a predictive factor of limb loss. When individual pathogens were studied as predictive factors for limb loss, none were found to be predictive of limb loss (P> 0.050). However, Fejfarova et al. 24 found S. aureus to be a significant predictive factor for limb loss. Wheat et al. 25 has shown that deep-tissue biopsy were likely to contain a single organism, as compared to superficial wound culture, which were more likely to be polymicrobial. Hence, the higher amputation rate in patients having monomicrobial infections could be contributed by the fact that patients with more severe infections often undergo surgical intervention and more likely to have deep tissue (intra-operative) cultures. Limb loss occurred in 42.1% of patients with WBC ≥ 15.0×10⁹/L. WBC ≥ 15.0×10⁹/L was found to be a significant predictive factor for limb loss (P= 0.014). Limb loss occurred in 41.5% of patients with ESR ≥ 100 mm/hr. Table 1 showed that ESR ≥ 100 mm/hr was also a significant predictive factor for limb loss (P= 0.001) Limb loss occurred in 46.2% of patients with CRP ≥15.0 mg/dL. CRP ≥15.0 mg/dL was also found to be a significant predictive factor for limb loss (P= 0.017). Limb loss occurred in 51.6% of patients with Hb ≤10.0g/dL. It was interesting to note that Hb ≤10.0g/dL was a highly significant predictive factor for limb loss (P< 0.001). Limb loss occurred in 51.7% of patients with Cr ≥150 µmol/l. Cr ≥150 µmol/l was found, as shown in Table 1, to be a highly significant predictive factor for limb loss (P= 0.001). Pittet et al. 21 and Upchurch et al. 26 showed that elevated CRP levels and elevated Cr levels were useful in signalling severe infection and predicting limb loss. However, a study by Santos et al. 14 did not find Cr, glucose and WBC levels to be significant risk factors for major amputations. Limb loss occurred in 24.1% of patients with HbA1c >7.0%. Table 1 showed that HbA1c was not found to be a predictive factor for limb loss (P> 0.050). Glycemic control is commonly found to be of key importance to the prevention of major amputations 8 27, although HbA1c was not found to be a predictive factor in our study. This is the most comprehensive study about DFIs undertaken in Singapore in recent years and hope that it will provide awareness of the rising rate of diabetes mellitus and its related lower extremity amputations. The authors have not received any funding or benefits from industry to conduct this study. Ministry of Health Singapore. (2004). Details of national health survey 2004 findings. Available from: http://www.moh.gov.sg/mohcorp/uploadedfiles/News/Current_Issues/2005/Apr/Details_of_NHS_04_findings.pdf [cited 1 May 2011] Ministry of Health Singapore. (2001). Epidemiology and disease control division. Annual Report 2001. Available from: http://www.moh.gov.sg/mohcorp/uploadedfiles/Publications/Reports/2002/nhss_2001.pdf [cited 1 May 2011] Shah BR Hux JE. Quantifying the risk of infectious diseases for people with diabetes Diabetes Care 2003 26 510 13 Lee WRW. The changing demography of diabetes mellitus in Singapore Diabetes Res Clin Prac 2000 50 S35 S39 Tan CE Emmanuel SC Tan BY Jacob E. Prevalence of diabetes and ethnic differences in cardiovascular risk factors. The 1992 Singapore National Health survey Diabetes Care 1999 22 241 7 Thai AC Yeo PP Lun KC Hughes K Ng WY Lui KF Diabetes mellitus and its chronic complications in Singapore: an increasing healthcare problem Ann Acad Med Singapore 1990 19 517 23 Bose K. Infection in diabetic foot Ann Acad Med Singapore 1978 7 359 65 Cheah JS Thai AC Alli R Chan L Wang KW Yeo PP. Infections in diabetes with special reference to diabetics in Singapore Ann Acad Med Singapore 1985 14 240 6 Lee EH Bose K. Orthopaedic management of diabetic foot lesions Ann Acad Med Singapore 1985 14 331 3 Singapore Department of Statistics (2005). General Household Survey 2005. http://www.singstat.gov.sg/pubn/popn/ghsr1/t1.pdf [cited 1 May 2011] Bose K. A surgical approach for the infected diabetic foot Int Orthop 1979 3 177 81 Frykberg RG. An evidence-based approach to diabetic foot infections. Am J Surg 2003; 186: 44S–54S; discussion 61S–64S. Leung HB Ho YC Carnett L Lam PKW Wong WC. Diabetic foot ulcers in the Hong Kong Chinese population: retrospective study Hong Kong Med J 2001 7 350 5 Santos VP Silveiria DR Caffaro RA. Risk factors for primary major amputations in diabetic patients Sao Paulo Med J 2006 124 66 70 Miyajima S Shirai A Yamamoto S Okada N Matsushita T. Risk factors for major limb amputations in diabetic foot gangrene patients Diabetes Res Clin Pract 2006 71 272 9 Gurlek A Bayraktar M Savas C Gedik O. Amputation rate in 147 Turkish patients with diabetic foot: the Hacettepe University Hospital experience Exp Clin Endocrinol Diabetes 1998 106 404 9 Hamalainen H Ronnemaa T Halonen JP Toikka T. Factors predicting lower extremity amputations in patients with Type 1 or Type 2 diabetes mellitus: a population based 7-year follow-up study J Intern Med 1999 246 97 103 Resnick HE Valsania P Philips CL. Diabetes mellitus and nontraumatic lower extremity amputations in black and white Americans Arch Intern Med 1999 159 2470 5 Leggetter S Chaturvedi N Fuller JH Edmonds ME. Ethnicity and risk of diabetes-related lower extremity amputation Arch Intern Med 2002 162 73 8 Nather A , Chionh SB , Wong KL , Koh SQ , Chan YH , Li XY , Socioeconomic profile of diabetic patients with and without foot problems. Diabetic Foot and Ankle 2010; 1: 5523. DOI: 10.3402/dfa.v1i0.5523 Pittet D Wyssa B Herter-Clavel C Kursteiner K Vaucher J Lew PD. Outcome of diabetic foot infections treated conservatively Arch Intern Med 1999 159 851 6 Reiber GE Vileikyte L Boyko EJ Aguila MD Smith DG Lavery LA Causal pathways for incident lower-extremity ulcers in patients with diabetes from two settings Diabetes Care 1999 22 157 62 Mayfield JA Caps MT Boyko EJ Ahroni JH Smith DG. Relationship of medial arterial calcinosis to autonomic neuropathy and adverse outcomes in a diabetic veteran population J Diabetes Complications 2002 16 165 71 Fejfarova V Jirkovska A Skibova J Petkov V. Pathogen resistance and other risk factors in the frequency of lower limb amputations in patients with the diabetic foot syndrome Vnitr Lek 2002 48 302 6 Wheat LJ Allen SD Henry M Kenek CB Siders JA Kuebler T. Diabetic foot infections. Bacteriologic analysis Arch Intern Med 1986 146 1935 40 Upchurch Jr GR Keagy BA Johnson Jr G. An acute phase reaction in diabetic patients with foot ulcers Cardiovasc Surg 1997 5 32 6 Caputo GM Cavanagh PR Ulbrech JS Gibbons GW Karchmer AW. Assessment and management of foot disease in patients with diabetes N Engl J Med 1994 331 854 60