An open randomized controlled trial of desmopressin and pulse dexamethasone as adjunct therapy in patients with pulmonary involvement associated with severe leptospirosis

Authors


Corresponding author and reprint requests: Y. Suputtamongkol, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
E-mail:siysp@mahidol.ac.th

Abstract

Clin Microbiol Infect 2010; 16: 1207–1212

Abstract

Pulmonary involvement in leptospirosis is emerging as a common complication of severe leptospirosis. A prospective randomized controlled trial of desmopressin or high-dose (pulse) dexamethasone as adjunctive therapy in 68 patients with pulmonary involvement associated with severe leptospirosis was conducted between July 2003 and October 2006 at five hospitals in Thailand. There were 23 patients in the desmopressin group, 22 in the pulse dexamethasone group, and 23 in a control group who received standard critical care alone. The diagnosis of leptospirosis was confirmed in 52 patients (77%). There were 15 deaths (22%), of which eight patients received desmopressin, four patients received pulse dexamethasone, and three patients received critical care alone (p 0.19). Eight patients with confirmed leptospirosis died (five patients in the desmopressin group, one in the pulse dexamethasone group and two in the control group). The mortality was not significantly different in the desmopressin group or pulse dexamethasone group compared to the control group in both intention-to-treat patients, and in patients with confirmed leptospirosis. There were no serious events associated with desmopressin treatment, although pulse dexamethasone treatment was associated with a significant increase in nosocomial infection. The results of logistic regression analysis revealed that serum bilirubin level was the only significant risk factor associated with mortality (OR 0.759, 95% CI 0.598–0.965, p 0.024). The results obtained in the present study do not support the use of either pulse dexamethasone or desmopressin as adjunct therapy for pulmonary involvement associated with severe leptospirosis.

Introduction

Leptospirosis is a zoonosis, with a worldwide distribution, caused by pathogenic members of genus Leptospira. Clinical manifestations of human leptospirosis vary from subclinical infection, self-limited anicteric febrile illness, to a severe and potentially fatal illness known as Weil’s syndrome [1].

Pulmonary involvement in leptospirosis has been reported to be increasing, and is emerging as the main cause of death in this disease in many countries, including Thailand. The reported mortality rate of severe pulmonary involvement is in the range 40–75% [2–6]. The pathogenesis of lung abnormalities in leptospirosis is not completely understood. Two main mechanisms have been suggested: a toxin-mediated capillary vasculitis [7] and/or exacerbated immune responses of the host [8,9]. On the basis of this proposed pathogenic mechanism of lung injuries, high-dose or pulse dexamethasone and methylprednisolone have been used in patients with severe pulmonary involvement of leptospirosis [10,11]. Desmopressin, a selective vasopressin V2 receptor agonist, has been used successfully to improve haemostatic deficiencies in mild hemophilia A, Type I von Willebrand disease, platelet disorders, and in acquired bleeding as a result of renal failure, or hepatic cirrhosis [12]. Desmopressin and high-dose gluocorticosteroid were shown to be potential adjunctive treatments for leptospirosis in uncontrolled case series [10,11,13]. In the present study, we report a prospective randomized trial aiming to evaluate the efficacy of pulse dexamethasone or desmopressin as adjunct treatment in patients with pulmonary involvement associated with severe leptospirosis.

Materials and Methods

Patients and study sites

The study was conducted at five hospitals in Thailand, four in the northeast (Udon Thani Hospital, Udon Thani Province; Maharat Nakhon Ratchasima Hospital, Nakhon Ratchasima Province; Loei Hospital, Loei Province; and Chaiyapoom Hospital, Chaiyapoom Province) and one in the south (Chumphon Hospital, Chumphon Province). Inclusion criteria were adult patients (>14 years) with suspected severe leptospirosis, defined as patients presenting with acute fever (oral temperature, ≥38.0°C for <15 days) in the absence of an obvious focus of infection, and who, in the opinion of the attending physician, might have pulmonary involvement (i.e. history of haemoptysis and/or bilateral nodular or air space infiltration). Patients who were pregnant or breastfeeding, those with history of bleeding disorder, those who had underlying diseases such as chronic liver disease or diabetes mellitus, and those receiving diuretics or glucocorticoids were excluded. The study protocol was approved by the Ethical Review Subcommittee of the Public Health Ministry of Thailand and written informed consent was obtained from all of the study volunteers.

Sample size requirements

The study was designed to evaluate the efficacy of desmopressin and high-dose (pulse) dexamethasone as adjunct treatment for pulmonary involvement associated with severe leptospirosis compared to standard critical care (controls). Twenty-three patients in each group were required to detect a reduction in mortality from 60% in the control group to 20% in either desmopressin or pulse dexamethasone adjunct treatments with 95% confidence and 80% power.

Randomization and study protocol

Patients were randomly allocated to receive either 0.3 μg/kg of desmopressin in 50 mL of saline, as a 30-min infusion (desmopressin group); or 200 mg of intravenous infusion of dexamethasone once daily for 3 days followed by 1 mg/kg/day oral prednisolone for 4 days (pulse dexamethasone group); or neither (control group). Desmopressin could be repeated two or three times at 12- or 24-h intervals if bleeding persisted. Dosage regimens of desmopressin and dexamethasone used in the study were based on published case series [10,13]. All patients received a combination of ceftriaxone or cefotaxime and doxycycline during the first 48 h of admission. Treatment was then continued or switched to other antimicrobials according to results of the initial blood cultures. Other supportive measures were provided based on the decision of the attending physician.

Baseline investigations included history, clinical examination, a full blood count, plasma glucose and electrolytes, serum urea and creatinine, liver function tests, prothrombin time and activated partial thromboplastin time, two aerobic blood cultures, urine analysis and chest radiography. An additional 5 mL of blood was placed into a sterile EDTA bottle for a PCR assay. Patients who were admitted with acute respiratory distress or multi-organ dysfunction, and/or required mechanical ventilation, were admitted to the intensive care unit as soon as possible.

Patients were discharged when the oral temperature had fallen to ≤37.5°C for at least 48 h. Convalescent sera for serological assays were collected 1–2 weeks after discharge. Sera were stored at −20°C until tested. Plasma from EDTA blood was stored at −70°C until tested. Data collection was carried out by the study team, who were unaware of the study hypothesis.

Confirmation of leptospirosis

Leptospirosis was confirmed by the World Health Organization criteria [14]. Acute and follow up sera were tested by the microscopic agglutination test (MAT), as previously described [14]. Reference Leptospira from 24 serogroups including serovars known to be prevalent in Thailand were used as the antigen in the MAT. A PCR assay targeting specific outer membrane protein (lipL21) of Leptospira was performed as previously described [15]. The diagnosis of leptospirosis was made by either positive PCR or either a four-fold or greater rise in antibody titre, or a titre of at least 1 : 400 on a single specimen.

Criteria for the diagnosis of rickettsial infections (scrub typhus and murine typhus) were either at least a four-fold rise in specific anti-rickettsial IgG or IgM (using an immunofluorescent antibody test.) titre between paired serum samples to a titre of at least 1 : 200, or a single titer or stable IFA titre of 1:400 or greater [16].

Patients with confirmed leptospirosis were classified prospectively by organ system involvement manifested by hypotension (systolic blood pressure of <90 mmHg or a sustained decrease in systolic blood pressure ≥40 mmHg); jaundice (a rise in total bilirubin to ≥50 μmol/L (normal range 5–17 μmol/L); renal dysfunction (either oliguria i.e. urine output <0.5 mL/kg/h for at least 1 h, or azotemia (serum creatinine of ≥265 μmol/L); pulmonary involvement (abnormal chest radiograph or requirement for mechanical ventilation on admission); decreased level of consciousness; or hemorrhagic complications such as haemoptysis, or gastrointestinal bleeding.

Analysis of results

The efficacy of desmopressin or pulse dexamethasone was analyzed on an intention-to-treat and a per-protocol basis. Intention-to-treat analysis was based on all patients who were enrolled into the study. Per-protocol analysis was performed for patients with laboratory-confirmed leptospirosis. The primary outcome measure was mortality rate. The secondary efficacy outcomes were the duration of mechanical ventilation in days and the duration of bleeding measured in hours from the time of enrollment to the last recorded presence of blood in body secretions or excreta.

Adverse events were defined as the development of new symptoms or signs after the administration of a study drug. Analyses of baseline characteristics and adverse events were performed on an intention-to-treat basis.

Statistical analysis

All statistical analyses were performed using SPSS, version 13.5 (SPSS Inc, Chicago, IL, USA). Chi-square or Fisher’s exact tests were used to compare rates and proportions and Mann–Whitney U- and unpaired t-tests were used to analyze continuous variables. All p values were two tailed; p ≤0.05 was considered as statistically significant. Outcomes were compared between each adjunct treatment group and logistic regression analysis was used to determine independent risk factors for death.

Results

The present study was performed between July 2003 and October 2006. The trial was stopped early because of difficulty in enrollment as a result of a reduction in the number of patients with suspected severe pulmonary involvement associated with leptospirosis over time. A total of 68 patients were studied (23 patients in the desmopressin group, 22 in the pulse dexamethasone group and 23 in the control group). The diagnosis of leptospirosis was confirmed in 52 patients (77%) by PCR in nine patients and by MAT in 43 patients. Of the 16 patients who were not diagnosed as having leptospirosis, six had rickettsial infections (scrub typhus in five and murine typhus in one) and two had septicaemic melioidosis; the final diagnosis was unknown in eight patients.

Demographic data, baseline clinical characteristics and laboratory investigations on admission were comparable between the groups (Table 1). All patients received ceftriaxone or cefotaxime plus doxycycline treatment during the first 48 h. Other supportive measures were similar in the three study groups (Table 2).

Table 1. Demographic data, clinical characteristics and baseline laboratory tests on admission
 DesmopressinPulse dexamethasoneControl
  1. Data are available in 14/23, 14/22 and 14/23 patients of the desmopressin, pulse dexamethasone, and control group, respectively.

  2. *p values were >0.05 in all variables compared among the three study groups.

Total232223
Male, n (%)19 (83)20 (91)21 (91)
Median age, years (range)40 (16–73)38 (18–64)34 (16–60)
Median days of illness (range)5 (1–8)5 (2–14)4.5 (1–7)
Vital signs, median (range)
 Body temperature (°C)37 (36–40.3)36.7 (35.7–40.3)37 (35–39.5)
 Respiration rate/min24 (20–36)28 (20–40)24 (20–2)
 Mean arterial pressure (mmHg)70 (40–110)76 (50–110)75 (17–102)
Haemoptysis, n (%)19 (83)19 (86)20 (87)
Jaundice, n (%)17 (74)15 (68)15 (65)
Renal dysfunction, n (%)20 (87)16 (73)19 (83)
Thrombocytopenia, n (%)18 (78)13 (59)20 (87)
Abnormal chest X-ray, n (%)21 (91)22 (100)20 (87)
Laboratory results, median (range)
 Haematocrit (%)31.2 (14.8–46)31.3 (14.8–56)31.6 (23.6–45.9)
 White blood cell (× 103/L)13.1 (3.6–37.1)13.7 (4.4–42.3)10.5 (1–34.8)
 Platelets (× 109/L)42.5 (10–280)45 (9–538)32.5 (10–158)
 Total bilirubin (μmol/L)69.7 (3.4–443.7)120.7 (5.1–589.9)93.5 (10.2–518.5)
 Serum creatinine (μmol/L)319.2 (79.8–886.7)319.2 (53.2–1560)416.7 (62.1–1135)
 Maximum creatinine (μmol/L)416.7 (97.5–1090.5)390.1 (88.7–1622.5)523.1 (115.3–1134.8)
 Worst PaO2/FiO2 ratio*152.5 (59–456.7)143.3 (45–695.2)122 (57–458.3)
Table 2. Treatment and outcome of the three study groups (intention-to-treat)
OutcomeDesmopressinPulse dexamethasoneControlp value
Mechanical ventilation, n (%)13 (57)17 (77)16 (69.6)0.28
Other adjunctive treatment, n (%)
 Platelet transfusion10 (43)10 (46)14 (60.9)0.42
 Vitamin K injection9 (39)13 (59)11 (48)0.38
 Dopamine infusion16 (69.6)13 (59)16 (70)0.69
 Hemodialysis5 (21.7)6 (6)7 (30)0.79
Survived, n (%)15 (65.2)18 (82)20 (87)0.18
 Died within 24 h512 
 In confirmed leptospirosis cases12/17 (71)14/15 (93)18 (90)0.14
Median duration (range) of
 Mechanical ventilation (days)5 (1–17)6 (1–25)7 (1–17)0.35
 Bleeding after enrollment (h)72 (24–168)72 (8–138)96 (12–240)0.18
 Admission (days)7 (1–19)10.5 (2–34)9 (1–30)0.05
Adverse event
 No21 (91)14 (64)22 (96)0.04
 Yes
  Nosocomial infection061 
  Hyperglyceamia010 
  Hyponatraemia100 
  Rash100 
  Intracranial haemorrhage010 

Fifteen patients died (22%), of whom eight were in the desmopressin group, four were in the pulse dexamethasone group and three were in the control group (p=0.19). Seven of the deaths occurred within 48 h of admission. The diagnoses in patients who died were leptospirosis in eight, scrub typhus in three and unknown in four. Abnormal chest radiographs were found in 13 patients who died (cardiomegaly and appearances consistent with congestive heart failure in three, bilateral alveolar infiltration in nine and mixed reticular and alveolar infiltration in one). All but one patient who died had acute renal failure, and ten of 15 (67%) had jaundice. The cause of death was multi-organ failure in 13 patients. Nosocomial pneumonia was the cause of death in two patients with confirmed leptospirosis, both of whom had received pulse dexamethasone. In laboratory-confirmed leptospirosis, two deaths occurred in the control group compared to five in the desmopressin group and one in the pulse dexamethasone group.

A Cox proportional hazard model was used to predict the outcome of treatment adjusted for age, sex, duration of illness, systolic blood pressure, respiration rate, serum creatinine, serum total bilirubin, serum potassium and platelet count on admission. Serum creatinine was a significant risk factor associated with mortality in intention-to-treat patients, whereas serum total bilirubin was significantly associated with mortality in patients with laboratory-confirmed leptospirosis (Table 3). Adjunct treatment with either pulse dexamethasone or desmopressin did not affect the outcome.

Table 3. Results of logistic regression analysis to determine the independent risk factor for mortality in all study patients, and in patients with confirmed leptospirosis
FactorAll patientsConfirmed leptospirosis
OR* (95% CI)p valueOR* (95% CI)p value
  1. *Adjusted.

Age1.035 (0.987–1.085)0.1550.998 (0.916–1.087)0.962
Duration of fever1.066 (0.775–1.467)0.6930.914 (0.488–1.711)0.779
Systolic blood pressure1.013 (0.986–1.041)0.3461.013 (0.965–1.063)0.610
Respiration rate1.051 (0.947–1.167)0.3481.083 (0.965–1.063)0.353
Adjunct treatment
 Pulse dexamethasone0.354 (0.05–2.501)0.2980.036 (0.001–2.45)0.123
 Desmopressin2.438 (0.495–12.00)0.2731.582 (0.086–29.23)0.758
Serum potassium0.82 (0.371–1.813)0.6241.887 (0.66–5.397)0.236
Serum creatinine1.28 (1.036–1.581)0.0221.277 (0.834–1.954)0.260
Total bilirubin0.92 (0.841–1.007)0.0710.759 (0.598–0.965)0.024

Discussion

Severe manifestations of leptospirosis are hepatorenal dysfunction, sepsis syndrome, and bleeding (such as haemoptysis or hematemesis) [2–6]. Diffuse alveolar haemorrhage presenting as haemoptysis and dyspnea is the most serious pulmonary complication. The reported incidence of severe pulmonary haemorrhage associated with leptospirosis has varied from 3.7% (with 70% mortality) in Peru [17] to 19% (with 42% mortality) in the Seychelles [4]. The cause of death was either massive pulmonary haemorrhage or acute respiratory distress syndrome or multi-organ failure. The present study showed that Orientia tsutsugamushi (the causative organism of scrub typhus) and Burkholderia pseudomallei (the causative organism of melioidosis) can also cause haemoptysis, pneumonitis, and multi-organ failure, mimicking severe leptospirosis.

The incidence and the mortality of severe pulmonary haemorrhage associated with leptospirosis have decreased over time in Thailand. An increased awareness amongst physicians in Thailand of severe leptospirosis has led to earlier antimicrobial treatment and aggressive intensive care therapy. This may explain the markedly lower overall mortality of severe leptospirosis in the present study compared to previous ones [4,17].

The inflammatory response in leptospirosis is relatively mild compared to the amount of vascular damage in severe cases. The presence of antibodies (IgG and IgA) and complement (C3), together with the paucity of leptospires in lung tissue found in both experimental animals [8] and autopsy material from patients who died with acute respiratory failure [9], suggests that infecting Leptospira might have precipitated an autoimmune process, leading to pulmonary haemorrhage through damage to the alveolar septa. High-dose steroid was found to be an effective adjunct to the treatment of severe pulmonary haemorrhage in patients with leptospirosis in two case series reported from India [9,10]. We could not confirm the efficacy of this adjunct treatment in this control study. Although the mortality in the high-dose dexamethasone group was not significantly different from the controls, dexamethasone treatment was associated with nosocomial pneumonia in two patients.

The whole-genome sequencing of Leptospira interrogans serovars lai has suggested alternative pathogenic mechanisms. Genes encoding several proteins with homology to animal proteins important in haemostasis were identified, including platelet-activating factor acetylhydrolase and von Willebrand factor type A domains [18]. This organism may therefore directly activate the haemostasis pathway. Desmopressin triggers the release of endothelial haemostatic factors, shortens prolonged bleeding times, enhances platelet adhesiveness to injured vessels, and induces von Willebrand factor secretion by activating endothelial cell V2 receptors. These receptors have been identified recently in human lung tissues and cultured human lung microvascular endothelial cells [19]. Desmopressin has also proved to be effective in the bleeding associated with hepatic and renal failure [12], and this also supports its use in patients with leptospirosis. However, although other studies have reported desmopressin to be an effective adjunct to the treatment of massive pulmonary haemorrhage in patients with leptospirosis [13], we did not confirm this in the present randomized controlled trial.

The present study was conducted in a subgroup of patients who had severe leptospirosis, most of whom had multi-organ dysfunction on admission. Despite desmopressin or pulse dexamethasone adjunct therapy, eight patients with laboratory-confirmed leptospirosis died, most of them within 48 h of admission from irreversible multi-organ failure. Although they presented with haemoptysis and bilateral pulmonary infiltrates consistent with diffused alveolar haemorrhage, massive lung haemorrhage was not found to be a main cause of death in these patients. This suggests that the pathogenesis of multi-organ failure and septic shock in leptospirosis is similar to septic shock caused by other bacteria and that this was not affected by desmopressin or pulse dexamethasone.

The observed mortality in the present study was much less than expected and the number of patients with confirmed leptospirosis did not reach the target number. Therefore, the present study has limited statistical power to detect treatment differences in patient with confirmed leptospirosis. However, the results obtained in the present study do not support the use of either high-dose dexamethasone or desmopressin as the adjunctive treatment of pulmonary involvement associated with severe leptospirosis. Early diagnosis and aggressive critical care supportive therapy are key factors in the reduction of mortality in these patients.

Acknowledgements

The authors thank the doctors, nurses and medical technologists of Udon Thani Hospital, Maharat Nakhon Ratchasima Hospital, Chaiyapoom Hospital, Loei Hospital, and Chumphon Hospital for their cooperation and help during the study period. The authors also thank N. Day and S. Peacock for their help and suggestions during the study period and in the manuscript preparation.

Transparency Declaration

The Thailand Research Fund, the Ministry of Public Health, Thailand and the Wellcome Trust of Great Britain funded the present study. The study was partly supported by the Mahidol-Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University. The funding sources had no role in designing or conducting the study, the collection and evaluation of the data, the writing of the manuscript, or the submission of the manuscript for publication. The corresponding author had full access to all of the data in the study and had final responsibility for the decision to submit for publication. There are no dual or conflicting interests to declare.

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