Validation of a clinical trial composite endpoint for patients with necrotizing soft tissue infections

Reported outcome measures in necrotising soft tissue infections: a systematic review

Introduction

There are inconsistencies in outcome reporting for patients with necrotising soft tissue infections (NSTI). The aim of this study was to evaluate reported outcome measures in NSTI literature that could inform a core outcome set (COS) such as could be used in a study of hyperbaric oxygen in this indication.

Methods

A systematic review of all NSTI literature identified from Cochrane, Ovid MEDLINE and Scopus databases as well as grey literature sources OpenGrey and the New York Academy of Medicine databases which met inclusion criteria and were published between 2010 and 2020 was performed. Studies were included if they reported on > 5 cases and presented clinical endpoints, patient related outcomes, or resource utilisation in NSTI patients. Studies did not have to include intervention. Two independent researchers then extracted reported outcome measures. Similar outcomes were grouped and classified into domains to produce a structured inventory. An attempt was made to identify trends in outcome measures over time and by study design.

Results

Three hundred and seventy-five studies were identified and included a total of 311 outcome measures. Forty eight percent (150/311) of outcome measures were reported by two or more studies. The four most frequently reported outcome measures were mortality without time specified, length of hospital stay, amputation performed, and number of debridements, reported in 298 (79.5%), 260 (69.3%), 156 (41.6%) and 151 (40.3%) studies respectively. Mortality outcomes were reported in 23 different ways. Randomised controlled trials (RCTs) were more likely to report 28-day mortality or 90-day mortality. The second most frequent amputation related outcome was level of amputation, reported in 7.5% (28/375) of studies. The most commonly reported patient-centred outcome was the SF-36 which was reported in 1.6% (6/375) of all studies and in 2/10 RCTs.

Conclusions

There was wide variance in outcome measures in NSTI studies, further highlighting the need for a COS.

Duration of Antibiotic Therapy in Necrotizing Soft Tissue Infections: Shorter is Safe

Background: Early debridement improves outcome in necrotizing soft tissue infection (NSTI), but there is no consensus on duration of antimicrobial therapy. We recently changed practice to discontinue antibiotic agents early with a goal of 48 hours after adequate source control. We hypothesized that discontinuing antibiotic agents after a short course is safe in the treatment of NSTI. Patients and Methods: This was a prospective study of patients with NSTI comparing short duration of antibiotic agents to a control population after a change in practice. In 2018 we began discontinuing antibiotic agents within 48 hours of source control (absence of cellulitis and no evidence of active infection). Previously, antibiotic duration was at the discretion of the attending surgeon (generally 7-10 days). Patients were excluded from analysis if they were initially debrided at a referring facility, immune compromised, or died prior to source control. Patient characteristics and outcomes were evaluated. The primary outcome was treatment failure requiring antibiotic agents to be restarted with or without further debridement of infected tissue. Secondary outcomes included the duration of antibiotic therapy after source control. Results: We evaluated 151 patients; 119 admitted between January 1, 2011 and January 31, 2018 (PRE) and 32 admitted after January 31, 2018 (POST). Patients were not statistically different regarding characteristics, admission physiologic variables, and comorbidities. The median duration of antibiotic agents after source control in the PRE group was 180.3 hours (interquartile range [IQR], 100.7-318.8) versus 48 hours (IQR, 32.3-100.8) in the POST group (p < 0.01). Patients in each group were treated as described above, and treatment failure occurred in seven (5.9%) PRE patients and two (6.3%) POST (99.3% post hoc power at non-inferiority limit 20%, significance p < 0.05). Thirty-day all-cause mortality was not different between groups (6.7% vs. 6.3%; p = 0.94). Conclusions: Short-duration (48 hours) antibiotic agents after NSTI source control is as safe and effective as a longer course.

Evaluation of Antibiotic Duration after Surgical Debridement of Necrotizing Soft Tissue Infection

Background: Necrotizing soft tissue infection (NSTI) is known to be a medical emergency with high morbidity and mortality. Guidelines do not specify the optimal duration of antibiotic agents after completion of surgical debridements of NSTI, which has created variable practice. It was hypothesized that patients with NSTI who receive 48 hours or less of post-operative antibiotic agents after final debridement have similar rates of subsequent intervention or infection recurrence, suggesting that a shorter duration of antibiotic agents may treat NSTI adequately after final surgical debridement. Patients and Methods: This was a retrospective study including adults with NSTI identified through International Classification of Diseases, Ninth Revision (ICD-9), International Classification of Diseases, Tenth Revision (ICD-10), and Current Procedural Terminology (CPT) codes admitted to one academic institution between January 1, 2010 and July 31, 2020. Demographics, surgical practices, antibiotic practices, and clinical outcomes including inpatient mortality, hospital length of stay (LOS), intensive care unit (ICU) LOS, total antibiotic days, necrotizing infection clinical composite end point (NICCE) success, and infection recurrence were compared based on the duration of antibiotic agents after final debridement. Results: Three hundred twenty-two patients with NSTI were included and baseline characteristics and clinical severity markers were well balanced between the two groups. In 71 patients (22%) who received less than 48 hours of antibiotic agents after final debridement there was no difference in recurrence (1.4% vs. 3.6%; p = 0.697), mortality (1.4% vs. 4.4%; p = 0.476), or ICU LOS (1 vs. 2 days; p = 0.300], but they did have a shorter hospital LOS (7 vs. 10 days; p = 0.011). Conclusions: Shorter duration of antibiotic therapy after final surgical debridement of NSTI may be appropriate in patients without another indication for antibiotic agents.

A host-directed macrocyclic peptide therapeutic for MDR gram negative bacterial infections

The emergence of infections by carbapenem resistant Enterobacteriaceae (CRE) pathogens has created an urgent public health threat, as carbapenems are among the drugs of last resort for infections caused by a growing fraction of multi-drug resistant (MDR) bacteria. There is global consensus that new preventive and therapeutic strategies are urgently needed to combat the growing problem of MDR bacterial infections. Here, we report on the efficacy of a novel macrocyclic peptide, minimized theta-defensin (MTD)-12813 in CRE sepsis. MTD12813 is a theta-defensin inspired cyclic peptide that is highly effective against CRE pathogens K. pneumoniae and E. coli in vivo. In mouse septicemia models, single dose administration of MTD12813 significantly enhanced survival by promoting rapid host-mediated bacterial clearance and by modulating pathologic cytokine responses, restoring immune homeostasis, and preventing lethal septic shock. The peptide lacks direct antibacterial activity in the presence of mouse serum or in peritoneal fluid, further evidence for its indirect antibacterial mode of action. MTD12813 is highly stable in biological matrices, resistant to bacterial proteases, and nontoxic to mice at dose levels 100 times the therapeutic dose level, properties which support further development of the peptide as a first in class anti-infective therapeutic.

Resolution of organ dysfunction as a predictor of long-term survival in necrotizing soft tissue infections: Analysis of the AB103 Clinical Composite Endpoint Study in Necrotizing Soft Tissue Infections trial and a retrospective claims database-linked chart study

BACKGROUND

Necrotizing soft tissue infections (NSTIs) are an acute surgical condition with high morbidity and mortality. Timely identification, resuscitation, and aggressive surgical management have significantly decreased inpatient mortality. However, reduced inpatient mortality has shifted the burden of disease to long-term mortality associated with persistent organ dysfunction.

METHODS

We performed a combined analysis of NSTI patients from the AB103 Clinical Composite Endpoint Study in Necrotizing Soft Tissue Infections randomized-controlled interventional trial (ATB-202) and comprehensive administrative database (ATB-204) to determine the association of persistent organ dysfunction on inpatient and long-term outcomes. Persistent organ dysfunction was defined as a modified Sequential Organ Failure Assessment (mSOFA) score of 2 or greater at Day 14 (D14) after NSTI diagnosis, and resolution of organ dysfunction defined as mSOFA score of 1 or less.

RESULTS

The analysis included 506 hospitalized NSTI patients requiring surgical debridement, including 247 from ATB-202, and 259 from ATB-204. In both study cohorts, age and comorbidity burden were higher in the D14 mSOFA ≥2 group. Patients with D14 mSOFA score of 1 or less had significantly lower 90-day mortality than those with mSOFA score of 2 or higher in both ATB-202 (2.4% vs. 21.5%; p < 0.001) and ATB-204 (6% vs. 16%: p = 0.008) studies. In addition, in an adjusted covariate analysis of the combined study data sets D14 mSOFA score of 1 or lesss was an independent predictor of lower 90-day mortality (odds ratio, 0.26; 95% confidence interval, 0.13-0.53; p = 0.001). In both studies, D14 mSOFA score of 1 or less was associated with more favorable discharge status and decreased resource utilization.

CONCLUSION

For patients with NSTI undergoing surgical management, persistent organ dysfunction at 14 days, strongly predicts higher resource utilization, poor discharge disposition, and higher long-term mortality. Promoting the resolution of acute organ dysfunction after NSTI should be considered as a target for investigational therapies to improve long-term outcomes after NSTI.

LEVEL OF EVIDENCE

Prognostic/epidemiology study, level III.

Antibiotic Exposure Is Not Associated With Clearance of Bronchoalveolar Growth: Results From a Prospective Ventilator-Associated Pneumonia Study

BACKGROUND

Ventilator-associated pneumonia is poorly understood in trauma. Ventilated trauma patients can develop bacterial burden without symptoms; the factors that influence this are unknown.

METHODS

Injured adults ventilated for > 2 days were enrolled. Mini-bronchoalveolar lavage was performed for 14 days or until extubation. Semi-quantitative cultures were blinded from clinicians. All cultures with > 104 colony forming units (CFU) were assessed for antibiotic exposure (ABXE) and spectrum of coverage. mBAL CFU was assessed daily.

RESULTS

60 patients were ventilated for 9 days (median). There were 75 with > 104 CFU. 46 had > 104 CFU and no ABXE on the sample day. 74% had clearance or a decrease (CoD) in CFU without ABXE. 29 had > 104 CFU and ABXE on the sample day. 19 had ABXE with pathogen coverage. 84% had CoD in CFU. 10 had ABXE with no spectrum of coverage. 1/10 had increased CFU and the remaining 9/10 CoD in CFU. The three groups were not statistically different on chi-squared analysis.

CONCLUSION

Clearance of pathogens on surveillance cultures was unaffected by ABXE.

Competing risks analysis of time-to-event data for cardiovascular surgeons

OBJECTIVES

The purpose of this article is to provide thoracic and cardiovascular surgeons with a practical step-by-step strategy to use in collaboration with a biostatistician for implementation of competing risks analysis when analyzing time-to-event data. Patients may have an outside event that precludes the event of interest. Traditional time-to-event analysis incorrectly assumes noninformative censoring in this scenario, which will lead to invalid results and conclusions.

METHODS

The steps are (1) to determine whether competing risks analysis is needed, (2) to perform a nonparametric analysis, (3) to perform a model-based analysis, (4) to interpret the results, and (5) to compare to traditional survival analysis methods. We apply our approach to a hypothetical cardiovascular surgery example in determining the hazard of mortality after the stage 3 Fontan operation associated with prematurity among patients with hypoplastic left heart syndrome who had successful completion of Norwood stage 1 while incorporating mortality during the stage 2 bidirectional Glenn procedure as a competing risk. We apply nonparametric, semiparametric, and parametric methods.

RESULTS

Although Cox regression establishes prematurity as a significant risk factor of mortality after stage 3 (hazard ratio, 1.26; 95% confidence interval, 1.06-1.50; P = .009), the competing risks analysis with the Fine-Gray model accounting for mortality after stage 2 determines that prematurity is not a significant predictor (hazard ratio, 1.07; 95% confidence interval, 0.90-1.27; P = .467).

CONCLUSIONS

This article provides a practical step-by-step approach for making competing risks more accessible for cardiac surgeons collaborating with a biostatistician in analyzing and interpreting time-to-event data.

Scarce evidence of efficacy of hyperbaric oxygen therapy in necrotizing soft tissue infection: a systematic review

Background: Necrotizing soft tissue infection (NSTI) is a rare and potentially life-threatening disease. Rapid surgical intervention, antibiotics and intensive care are the mainstay of treatment. Hyperbaric oxygen therapy (HBOT) is used as adjuvant therapy in some centres but there is a lack of research-based evidence of efficacy. Methods: Following the PRISMA guideline we conducted a systematic review on the efficacy of HBOT on NSTI with mortality as primary outcome. Through January 2019 major databases were searched and relevant literature assessed. The criteria for study inclusion were research of any design and any period of time comparing HBOT vs. non-HBOT in a population of NSTI-patients. Studies were analysed using the modified Delphi method and risk of bias in non-randomized studies - of interventions tool. Relative risk (RR) on mortality was calculated for each study individually. Results: A number of 1733 studies were identified through database search. Ultimately, 21 studies were included of which 19 were case series with a control group. The majority of the studies performed poor in quality assessment and all featured a high to critical risk of bias. The association of HBOT on mortality was generally reported as positive, however, the results should be considered with great scepticism. Conclusions: The evidence of HBOT in NSTI is poor and biased. There is a strong need for randomized controlled trials (RCTs) to shed light on a potential life-saving treatment.

Primary Endpoints in Pediatric Efficacy Trials Submitted to the US FDA

The selection of appropriate endpoints in pediatric drug development trials is a critical aspect of trial design. Given the high pediatric trial failure rate, selecting optimal trial design elements, such as the primary efficacy endpoint, is essential to ensuring increased potential for trial success. The objectives of this study were to identify the primary efficacy endpoints measured in pediatric drug development trials submitted to the US Food and Drug Administration and to relate endpoint attributes to trial and label outcome. The analysis included pediatric pivotal efficacy studies submitted from September 2007 to July 2016 for which there was a corresponding adult trial for the same indication. Two hundred and thirty-four efficacy trials on 138 unique products studied in pediatric patients were assessed. The adult and pediatric endpoints were the same in 141 of the 234 trials (60.3%), and these trials succeeded in meeting their primary endpoint more often (122 of 141 [86.5%]) than when the adult and pediatric endpoints differed (57 of 93 [61.3%]; odds ratio, 4.03; 95%CI, 2.10-7.80). Trials that included both pediatric and adult patients succeeded more frequently than those trials that did not combine pediatric and adult patients (85 of 95 versus 94 of 139, respectively; odds ratio, 4.05; 95%CI, 1.94-9.31). No differences were observed in pediatric trial success between those using subjective and objective endpoints. Using the same endpoint in the pediatric trial as was measured in the corresponding adult trial and enrolling pediatric and adult patients in the same trial were attributes associated with trial success.

Bacterial Burden in Critically Injured Ventilated Patients Does Not Correlate with Progression to Pneumonia

BACKGROUND

Ventilator-associated pneumonia (VAP) is common in critically injured patients. The pathogenesis of VAP is not completely understood. We hypothesized that mechanically ventilated trauma patients who develop pneumonia have a progressive increase in pathogen burden over the course of ventilation until a threshold for symptomatic pneumonia is reached, leading to clinical suspicion of VAP.

METHODS

Critically injured adults ventilated for more than two successive days were enrolled. Patients underwent daily surveillance mini-bronchoscopic alveolar lavage (mBAL) while ventilated for 14 days or until extubation. Standard semi-quantitative cultures were performed, and the investigators were blinded to the results. Standard patient management was performed by the clinical team. Patients suspected of having VAP by the clinical team underwent bronchoscopic bronchoalveolar lavage (bBAL) and semi-quantitative culture, with VAP defined as clinical symptoms plus >10⁴ colony-forming units (CFU) of bacteria. Standard statistical analysis for non-parametric data was performed.

RESULTS

The 37 patients enrolled were ventilated for a median of nine days. While ventilated, 23 patients met the criteria for a clinical suspicion of VAP, of which two were too ill for bronchoscopy. Thus, 21 patients underwent bBALs because of a suspicion of VAP, and 13 (35%) were positive, with >10⁴ CFU of one or more pathogens, and were treated for pneumonia. The bacterial burden on mBAL remained <10⁴ CFU during ventilation for 32% of patients. None developed clinical symptoms of VAP. Two-thirds (67%) had an mBAL bacterial burden of >10⁴ CFU without clinical suspicion of VAP. Half (56%) of positive surveillance cultures were followed by clinical VAP, confirmed by bBAL, all of which had identical pathogens on mBAL and bBAL. Almost half (44%) of the patients with positive surveillance mBALs never developed clinical VAP.

CONCLUSION

A significant percentage of critically injured, ventilated adults develop high bacterial burdens in the lungs early in their course, and many clear these bacteria without developing VAP. Further study is needed to identify the factors causing progression to VAP.