Outpatient Foot-Sparing Surgery Is Safe in Selected Patients with Diabetic Foot Infections

OBJECTIVE

To determine if outpatient foot-sparing surgery for patients with diabetic foot infections (DFIs) is associated with a higher rate of treatment failure or longer healing time.

METHODS

In this prospective observational study, the authors consecutively recruited a cohort of 200 patients with moderate and severe DFIs from the Diabetic Foot Unit of Hospital San Juan de Dios, Caja Costarricense de Seguro Social, San José de Costa Rica, Costa Rica from October 15, 2020 to December 15, 2021. They compared outpatients with those admitted. Cox univariate analysis was performed, with time to treatment failure and time to healing as dependent variables and outpatient management as the independent variable.

RESULTS

Seventy-one patients underwent surgery on an outpatient basis (35.5%), and 129 (64.5%) were admitted. Sixty of 111 patients (54.1%) with moderate infections were treated as outpatients versus 11 of 89 (12.4%) of those with severe infections. Twelve (16.9%) of the outpatients and 26 (20.2%) of those admitted presented failure (P = .57). The Cox univariate analysis with time to failure of treatment associated with outpatient management reported a hazard ratio of 1.26 (95% CI, 0.64-2.50; P = .50), and the analysis regarding healing time reported a hazard ratio of 0.91 (95% CI, 0.66-1.25; P = .56).

CONCLUSIONS

Foot-sparing surgery on an outpatient basis was safe in more than half the cases of moderate DFIs, especially in patients with osteomyelitis. This approach is not associated with treatment failure or a longer healing time. Patients with severe infections, penetrating injuries, necrosis, or high inflammatory response and those with peripheral arterial disease who require revascularizations should be admitted to the hospital.

Differences in Foot Infections Secondary to Puncture Wounds or Chronic Ulcers in Diabetes

We hypothesized that foot infections secondary to a puncture wounds (PWs) have a worse prognosis concerning infection-related mortality, recurrence of the infection, and healing than those secondary to a chronic ulcer. We conducted a prospective study consisting of 200 patients with moderate-to-severe diabetic foot infections. The cohort consisted of 155 men (77.5%) and 45 women (22.5%). The mean age of the patients was 59 years (standard deviation 12.2). Puncture wounds were the cause of the infection in 107 patients (53.5%) and a chronic ulcer was the cause in 93 patients (46.5%). One hundred and eleven patients (55.5%) had moderate and 89 (44.5%) had severe infections. Osteomyelitis was more frequently found in chronic ulcers (71%) than in PWs (44.9%), P < .001. Cox's survival analysis using PWs as an explanatory variable showed no association with infection-related mortality (hazard ratio [HR] 1.06, 95% confidence interval [CI] 0.32-3.46, P = .92), time to recurrence of infection (HR 0.64, 95% CI 0.27-1.51, P = .30), and time to healing (HR 0.81, 95% CI 0.60-1.08, P = .15). More than half of our patients had PWs as the mechanism by which the infection occurred. These patients usually had a lower rate of osteomyelitis but required hospitalization and antibiotic therapy more frequently than patients with infected chronic ulcers. We found no difference in outcomes between the 2 groups.

Residual osteomyelitis at the resection margin after conservative surgery is not associated with the recurrence of diabetic foot infection and may successfully be treated without postoperative antibiotic therapy

AIMS

We hypothesize that microbiology- and pathology-confirmed positive bone margins after the resection of diabetes-related foot osteomyelitis are associated with worse outcomes.

METHODS

We conducted a prospective study consisting of a cohort of 93 patients with diabetes-related foot osteomyelitis (histopathology confirmed) who underwent bone resection and where an additional bone biopsy was taken at the resection margin. The primary outcome was the recurrence of the infection.

RESULTS

Pathology-confirmed positive margins were detected in 62 cases (66.7%), microbiology-confirmed positive margins were detected in 75 cases (80.6%) and recurrence was detected in 19 patients (20.4%). Chi-squared test failed to show the presence of an association between the recurrence of the infection with pathology-confirmed positive margins (p = 0.82), with microbiology-confirmed positive margins, (p = 0.34) and with the use of postoperative antibiotics (p = 0.70). Healing in patients with pathology-confirmed positive margins was achieved in a median of 12 weeks (95% CI 9.2-18) and those with pathology-confirmed negative margins in 14.9 weeks (95% CI 10.2-21.9), Log-rank test, p = 0.74. Thirty-four patients out of 61 available for follow-up (55.7%) with pathology-confirmed positive margins were treated without postoperative antibiotics. In that group, Chi-squared test failed to show the presence of an association between the recurrence of the infection with the use of postoperative antibiotics (p = 0.47).

CONCLUSIONS

A positive margin was neither associated with the recurrence of the infection nor with the time to healing. More than half of patients with pathology-confirmed positive margins were treated without postoperative antibiotics and this approach was not associated with the recurrence of the infection.

Systemic Immune-Inflammation Index in Diabetic Foot Infections and Osteomyelitis

The systemic immune-inflammation index (SII) was significantly higher in patients with severe infections, those with necrosis, and in those requiring admission, postoperative antibiotics, and any amputation. However, SII was significantly lower in patients with osteomyelitis compared to those with soft tissue infections. The correlation coefficients (rho) between SII and other inflammatory markers were as follows: WBC (Moderate correlation, 0.64, P < .001), ESR (Weak correlation, 0.34, P < .001), and CRP (Moderate correlation, 0.56, P < .001). The correlation coefficient (rho) between SII and the number of days admitted was moderate, 0.42 (P < .001). Based on a previous experience, SII may be an additional marker to diagnose osteomyelitis in the feet of patients with diabetes. Now, we need further research including SII, a low-cost and easy-to-measure index, in well-designed controlled studies to definitively clarify its role.

Mean Platelet Volume-to-Lymphocyte Ratio Is a Biomarker of 1-Year Mortality in Patients With Diabetic Foot Infections

We aimed to evaluate the value of 2 peripheral blood cell ratios, the mean platelet volume-to-lymphocyte ratio (MPVLR) and the neutrophil-to-lymphocyte ratio (NLR) as prognostic biomarkers of mortality in patients with diabetic foot infections (DFIs). We conducted a prospective observational study consisting of a cohort of 200 patients with moderate to severe DFIs consecutively recruited from our Diabetic Foot Unit, Hospital San Juan de Dios, San José de Costa Rica, Costa Rica from October 15, 2020, to December 15, 2021. We studied the variables associated with one-year all-cause mortality using a multivariate backward Cox's regression model. Nonparametric Spearman Rho was used to study the linear correlation between NLR and MPVLR and other inflammatory markers. The variables associated with all-cause mortality were retinopathy (hazard ratio [HR]: 2.55, 95% confidence interval [CI]: 1.22-5.33, P = .01), estimated glomerular filtration rate (HR: 0.979, 95% CI: 0.969-0.990, P < .001), HbA1c (HR: 0.825, 95% CI: 0.702-0.969, P = .01), and MPVLR (HR: 1.093, 95% CI: 1.020-1.172, P = .01). NLR showed a strong correlation with white blood cell count (r = 0.60 [<0.001]) and c-reactive protein (r = 0.63 [<0.001]), and a weak correlation with erythrocyte sedimentation rate (r = 0.33 [<0.001]), though it was not associated with mortality. In conclusion, apart from other risk factors of mortality, we have for the first time demonstrated that the increasing value of MPVLR is a factor associated with one-year mortality in patients with DFIs.

Surgical Diabetic Foot Infections: Is Osteomyelitis Associated With a Worse Prognosis?

It has been reported that patients with diabetes and foot ulcers complicated with osteomyelitis (OM) have a worse prognosis than those complicated with soft tissue infections (STI). Our study aimed to determine whether OM is associated with a worse prognosis in cases of moderate and severe diabetic foot infections requiring surgery. A retrospective series consisted of 150 patients who underwent surgery for diabetic foot infections. We studied the differences between OM versus STI. Furthermore, diabetic foot infections were reclassified into four groups: moderate STI (M-STI), moderate OM (M-OM), severe STI (S-STI), and severe OM (S-OM). The variables associated with prognosis were limb loss, length of hospital stay, duration of antibiotic treatment, recurrence of the infection, and time to healing (both the initial ulcer and the postoperative wound). No differences in limb salvage, hospital stay, duration of antibiotic treatment, recurrence of the infection, and time to healing were found when comparing OM with STI. Patients with M-O had a higher rate of recurrences after initial treatment and a longer time to healing when comparing with M-STI. We didn't find any differences between severe infections with or without OM. In conclusion, we have found in our surgical series of diabetic foot infections that OM is not associated with worse prognosis when comparing with STI regarding limb loss rate, length of hospital stays, duration of antibiotic treatment, recurrence of the infection, and time to healing. The results of the present series should further be confirmed by other authors.

Does Metabolic Control Have Any Influence on the Clinical Presentation and Short-Term Outcomes of Diabetic Foot Infections?

Objective: We hypothesized that patients with poor glycemic control undergoing treatment for diabetic foot infections (DFIs) would have a poorer prognosis than those with better metabolic control assessed by glycated hemoglobin (HbA1c). Approach: We analyzed a retrospective cohort of 245 patients with moderate and severe DFIs. HbA1c values were dichotomized (<7% or ≥7% and ≤75th percentile (P75) and >P75) to analyze patient outcomes regarding metabolic control. The present study adhered to the STROBE guidelines for cohort studies. Results: One hundred sixty-nine patients (69%) were men. Their mean age was 60.7 years (10.8). HbA1c ≥7% was detected in 203 patients (82.9%). P75 HbA1c was 10.9%. After performing univariate analysis, we found an association of HbA1c <7% with major amputations and mortality. However, after applying the logistic regression model, we did not find HbA1c <7% to be a predictive factor of major amputation. The risk factors for mortality following application of Cox's proportional hazards model were osteomyelitis (HR: 0.2, 95% CI: 0.07-0.62, p < 0.01), eGFR <60 mL/min/1.73 m² (HR: 2.7, 95% CI: 1.0-7.5, p = 0.04), and HbA1c <7% (HR: 4.9, 95% CI: 1.8-13.2, p < 0.01). Innovation: The group with optimal glycemic control (HbA1c <7%) had a shorter survival time than those with worse metabolic control. Conclusions: We did not find a longer duration of hospitalization, a higher rate of amputations, or longer healing times in the groups with worse metabolic control. HbA1c <7% was a risk factor for mid-term mortality.

Clinical Features, Inflammatory Markers, and Limb Salvage in Older Adults with Diabetes-Related Foot Infections

Little information exists about diabetic foot infections (DFIs) in older patients. We hypothesize that older patients with DFIs have different clinical features and worse outcomes than younger patients. We conducted a prospective observational study consisting of a cohort of patients with diabetes and moderate to severe DFIs. Patients included in the cohort were dichotomized into two groups using percentile 75 (P75) of age as the cut-off value. Patients aged > P75 presented with more comorbidities and foot-related complications, a higher rate of peripheral arterial disease (PAD), worse renal function (higher values of blood urea nitrogen and creatinine, and lower values of estimated glomerular filtration rate), and lower values of HbA1c compared with younger patients. Infection severity, microbiological features, and inflammatory markers were similar in both groups. In the multivariate analysis, minor amputations were associated with age > P75 (OR = 2.8, 95% CI 1.3-5.9, p <0.01), necrosis (OR = 4.2, 95% CI 1.8-10.1, p < 0.01), and CRP values (OR = 1.045, 95% CI 1.018-1.073, p < 0.01). Major amputations were associated with a history of amputation (OR = 4.7, 95% CI 1.3-16.7, p = 0.01), PAD (OR = 4.3, 95% CI 1.2-14.6, p = 0.01), and albumin values (OR = 0.344, 95% CI 0.130-0.913, p = 0.03). In conclusion, limb salvage can be achieved in older patients with diabetes-related foot infections at the same rate as in younger patients, despite the fact that they have more comorbidities and foot-related complications, a higher rate of PAD, and worse renal function.

Surgery without postoperative antibiotic treatment in diabetic foot osteomyelitis is not associated with recurrence or limb loss

Not using antibiotics after surgical treatment of diabetic foot osteomyelitis was not associated with failure of the surgery, recurrences, or limb loss. Antibiotics were given in doubtful complicated cases such as severe infections, cases with necrosis, foul-smelling lesions and patients requiring revascularization.

Prospective Validation of the Value of Adding Osteomyelitis to Moderate and Severe Categories of Diabetic Foot Infections

We aimed to validate the value of adding osteomyelitis (OM) to moderate and severe categories of diabetic foot infections (DFIs) classification. We conducted a prospective study of a cohort of 200 patients with moderate and severe infections. Variables associated with prognosis were need for any amputation, major amputation, need for hospitalization, length of hospitalization, length of antibiotic therapy, reinfection rate and infection-related mortality. Infections were moderate in 111 cases (55.5%) and severe in 89 (44.5%). OM was diagnosed in 114 cases (57%), 73 presented as moderate (36.5%) and 41 as severe (20.5%). Overall, 129 patients (64.5%) were admitted for a median of 15 days (IQR 13) and 71 (35.5%) were treated as outpatients (day-surgery). Ninety-four patients (47%) were exclusively treated with intravenous antibiotics, 35 (17.5%) with intravenous and then shifting to oral, 16 (8%) exclusively with oral antibiotics, and 55 (27.5%) without antibiotics. Definitive surgery that led to the arrest of the infection was as follows: 117 patients (58.5%) underwent surgical debridement without amputation, and 69 (34.5%) underwent minor and 14 (7%) major amputation. Patients with OM presented as severe had a higher rate of amputations, major amputations, hospitalizations and need for antibiotic therapy when compared with OM presented as moderate. OM is strongly recommended to be added to the moderate and severe categories of the Infectious Diseases Society of America/International Working Group on Diabetic Foot severity system, as recommended by the International Working Group on Diabetic Foot 2019 guidelines.

Severe Diabetic Foot Infections without Systemic Inflammatory Response Syndrome. Prospective Validation of a New Category

We aimed to validate the prognostic value of subclassifying moderate diabetic foot infections into two categories: moderate and moderate/severe. We conducted a prospective study of a cohort of 200 patients with moderate and severe infections. Moderate infections were subclassified after applying a previously published score. Variables associated with prognosis were: need for any amputation, major amputation, need for hospitalization, length of hospitalization, length of antibiotic therapy, reinfection rate and infection-related mortality. Infections were moderate in 111 cases (55.5%) and severe in 89 (44.5%). Osteomyelitis was diagnosed in 114 cases (57%), 73 moderate (36.5%) and 41 severe (20.5%). Patients with severe OM had a higher rate of amputations, major amputations, hospitalizations and need for antibiotic therapy, and a longer duration of antibiotics when compared with moderate OM. After applying the score, moderate infections were subclassified into 73 moderate cases (65.7%) and 38 moderate/severe cases (34.3%). Moderate/severe had a higher rate of amputations, major amputations, hospitalizations and need for antibiotics than moderate ones. No differences regarding prognosis were found between moderate/severe and severe infections with systemic inflammatory response syndrome. Moderate/severe diabetic foot infections, which could also be known as severe infections without systemic inflammatory response syndrome, should be recognized as a new subgroup. We propose to merge severe diabetic foot infections with and without systemic inflammatory response syndrome into a unique category due to its prognostic value. Furthermore, osteomyelitis should be added to both moderate and severe new categories of diabetic foot infections. This article is protected by copyright. All rights reserved.

Clinical, microbiological and inflammatory markers of severe diabetic foot infections

AIMS

In addition to systemic inflammatory response syndrome (SIRS), various clinical signs, microbiological findings and inflammatory markers could be associated with severe diabetic foot infections (DFI).

METHODS

This study included a retrospective cohort of 245 patients with DFI treated at San Juan de Dios Hospital in San José de Costa Rica. Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), CRP/albumin ratio, peripheral blood leucocyte ratios and the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) scoring system were evaluated. Univariate analysis was carried out between moderate and severe infections. ROC curves were plotted. Cut-off value of inflammatory markers for diagnosing severe infections was established and then dichotomized to be included in a logistic regression model. A score was designed based on its results.

RESULTS

Skin necrosis (p < 0.01, OR = 8.5, 95% CI = 3.5-20.9), ESR > 94 mm/h (p < 0.01, OR = 2.5, 95% CI = 1.2-5.1), albumin < 2.8 g/dl (p = 0.04, OR = 2.0, 95% CI = 1.0-4.1) and neutrophil-to-lymphocyte ratio (NLR) > 4.52 (p < 0.01, OR = 3.3, 95% CI = 1.6-6.5) were found to be predictive of severe infections. Score >5 had a good diagnosis performance for classifying severe infections. Moderate infections with a score >5 had a worse prognosis than moderate ones.

CONCLUSIONS

We found an association of necrosis, serum albumin, ESR and NLR values with severe DFI. The presence of these predictive factors of severity in cases of moderate infections was significantly associated with a higher rate of amputations and recurrences, longer duration of antibiotic treatment and longer hospital stays. DFI could be classified as mild, moderate, severe without SIRS and severe.

Long-term Mortality of a Cohort of Patients Undergoing Surgical Treatment for Diabetic Foot Infections. An 8-year Follow-up Study

We analyzed a retrospective cohort of 150 patients with diabetic foot infections (DFIs) who underwent surgical treatment to determine long-term outcomes. The median follow-up of the series was 7.6 years. Cox's proportional hazards model for survival time was performed and hazard ratios (HRs) were estimated. Survival times were plotted using the Kaplan-Meier method. Fifteen patients (10%) required readmission after discharge from the hospital for a recurrence of the infection. Ninety patients (60%) had re-ulcerations. Forty-nine (54.4% of those re-ulcerated) required new admission and 24 of them (26.6% of those re-ulcerated) finally required a new amputation. Overall cumulative survival rates at 1, 5, and 8 years were 95%, 78%, and 64%, respectively. Predictive variables of long-term mortality were insulin treatment (HR: 2.0, 95% CI: 1.1-3.6, P = .01), female sex (HR: 3.1, 95% CI: 1.7-5.3, P<.01) and estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m² (HR: 2.2, 95% CI: 1.1-4.2, P = .01). In conclusion, patients undergoing surgical treatment for DFIs had a high rate of recurrences and mortality. Women, patients who underwent treatment with insulin, and those with eGFR <60 ml/min/1.73 m² had a higher risk of long-term mortality.