Low-dose versus high-dose methylprednisolone for children with severe Mycoplasma pneumoniae pneumonia (MCMP): Study protocol for a randomized controlled trial.

BACKGROUND: Severe Mycoplasma pneumoniae pneumonia (MPP) may develop with long-term pulmonary outcomes despite treatment with macrolides. Combined treatment with glucocorticoids can improve this outcome, though the optimal dosage is unknown. The aim of this study was to investigate the effects of low- and high-dose methylprednisolone in reducing the percentage of long-term pulmonary outcomes for children with severe MPP.
METHODS: A randomized, single-blind, parallel-controlled, multicenter clinical trial, methylprednisolone for children with severe M. pneumoniae pneumonia (MCMP), is being conducted in China. Pediatric patients (≤18 years of age, expected number = 402) admitted to the hospital with a clinical diagnosis of severe MPP and fulfilling inclusion and exclusion criteria are randomized (ratio of 1:1) to either a low-dose (2 mg/kg/d) or high-dose (10 mg/kg/d) methylprednisolone treatment group for 3 days followed by tapering of methylprednisolone over 12 days and combined with azithromycin. The primary composite outcome will be incidence of atelectasis, bronchiectasis, or bronchiolitis obliterans at 6-months after treatment. Secondary outcomes include recovery time of patient temperature, proportion of pulmonary lesions absorbed, changes of mucosa identified by bronchoscopy, length of hospital stay, pulmonary function and number of participant(s) needing intensive care. Assessments will be made at baseline, post-treatment and at 1-month, 3-month and 6-month follow-ups. DISCUSSION: This is the first randomized clinical trial designed to evaluate the safety and efficacy of low- versus high-dose methylprednisolone for reducing long-term pulmonary outcomes in pediatric patients with severe MPP. The results of this study will provide scientific evidence to guide clinical practice for the treatment of severe MPP. Trial registration: This study is registered at ClinicalTrials.gov (NCT02303587).

INTRODUCTION

Mycoplasma pneumoniae is one of the major pathogens causing community‐acquired pneumonia (CAP) in Chinese children, accounting for 47.8% of CAP in children of all ages. In children 5 years or older, M. pneumoniae accounts for over 70% of CAPS cases, which is higher than in the U.S. (19% in children over 5 years old).1, 2 The prognosis for patients with M. pneumoniae pneumonia (MPP) is usually good. However, cases of severe MPP are often complicated by multi‐organ damage (e.g. hepatitis, myocarditis, encephalitis) or serious long‐term pulmonary outcomes such as bronchiolitis obliterans, bronchiectasis, or atelectasis.3 It has been reported that the incidence of severe MPP in Chinese children has been increasing over the past ten years, reaching approximately 40% of all MPP cases.4, 5, 6, 7 The pathogenesis of severe MPP is unclear, though there is some evidence implicating excessive cytokine release and activation of cell‐mediated immune responses to the pathogen as well as development of macrolide resistance.8

Optimal treatment of children with s evere M PP is unclear. Recent studies have suggested that azithromycin combined with glucocorticoids may improve the prognosis of children with severe MPP.9, 10, 11, 12 Lee et al reported that when prednisolone (1 mg/kg/d for 3–7 days) was added to the treatment of children with severe or refractory MPP, the clinical status and radiographic findings were better than for children treated with azithromycin alone.13, 14 You et al15 and Tamura et al16 showed methylprednisolone (30 mg/kg/d) pulse therapy in patients with severe or refractory MPP quickly improved the radiological and laboratory abnormalities of these patients. Youn et al17 and You et al15 reported that high‐dose glucocorticoids (10 or 30 mg/kg/d) for patients with no response to low‐dose glucocorticoids (1 mg/kg/d) could induce clinical and radiographical improvement within 3 days. Other studies have shown that glucocorticoids dramatically benefit patients with severe MPP, this benefit is attributed to the anti‐inflammatory effects of glucocorticoids during M. pneumoniae infection.18

Considering the side effects of glucocorticoids on the pituitary body and adrenal cortex, low‐dose glucocorticoids (1–2 mg/kg) are used more widely in clinical practice for children with severe MPP. However, prospective studies to investigate superiority between low‐ and high‐dose glucocorticoid treatment are lacking. Appropriate methods and optimal dosage of glucocorticoids have not been fully clarified. Additionally, most reported studies used recent curative effect index rather than long‐term outcomes as the primary end point to evaluate the role of glucocorticoids.

We have conducted a pilot study of 32 pediatric patients with severe MPP, among them, 18 patients received low‐dose methylprednisolone (2 mg/kg/d) and 14 patients received high‐dose methylprednisolone (10 mg/kg/ d). After completion of the 6‐month follow‐up, the experimental results showed the incidence of long‐term pulmonary outcomes in the low‐dose group (50.0%, 9/18) was higher than in the high‐dose group (35.7%, 5/14). Patients in both groups had no adverse effects though this may be because of the low number of cases in our study. To further validate the use of methylprednisolone in patients with severe MPP, we are conducting the first large, randomized control trial (RCT) to assess the safety and efficacy of treatment with low‐ versus high‐dose methylprednisolone for reducing long‐term pulmonary outcomes in patients with severe MPP.

METHODS

Objectives

The first aim of our proposed multicenter, single‐blind, RCT is to evaluate low‐versus high‐dose methylprednisolone for reducing long‐term pulmonary outcomes of pediatric patients with severe MPP. We plan to evaluate whether high‐dose methylprednisolone treatment is superior to low‐dose methylprednisolone treatment for improving long‐term pulmonary outcomes in children with severe MPP. The second aim of our study is to demonstrate the safety of low‐ and high‐dose methylprednisolone treatment in children with severe MPP.

Study Design

Methylprednisolone for children with severe M. pneumoniae pneumonia (MCMP) is a randomized, single‐blind, parallel‐controlled, multicenter clinical trial. The overall design is shown in Figure 1. MCMP is registered at ClinicalTrials.gov (NCT02303587). Participants will be enrolled from six study centers in China from November 2014 to December 2018. Table 1 details the geographic region, sites and predicted numbers of hospitalized children with severe MPP for this study.

Figure 1

Study design flow diagram.

Table 1

Study centers and predicted numbers of hospitalized children with severe M. pneumoniae pneumonia

Centers	Hospitals	Number of patients
North China	Beijing Children's Hospital, Capital Medical University	150
	Capital Institute of Pediatrics	140
	Shanxi Children's Hospital	30
Northeast China	Shengjing Hospital of China Medical University	70
	Children's Hospital of Changchun	30
Northwest China	Women and Children's Health Hospital of yinchuan City	30

Ethics statement

Studies have shown that severe MPP patients are at a high risk to develop outcomes and may benefit from glucocorticoid therapy. Patients will be subject to continued follow‐up until they recover. Before randomization code allocation, the guardians of eligible patients will be asked to sign the informed consent, if the child is older than 10 years of age, he or she will be asked to sign the informed consent as well. The study protocol has been approved by the Ethics Committee of Beijing Children's Hospital, Capital Medical University, China (No: 2017‐k‐1).

Participants and recruitment procedure

All hospitalized patients less than 18 years old with severe MPP will be enrolled in this study. Diagnosis of severe MPP is based on clinical manifestations (fever, cough, wheezing), physical examination, serologic test (M. pneumoniae antibody detection using the passive agglutination [PA] method [Serodia‐Myco II, Fujirebio, Japan]), M. pneumoniae PCR test of nasopharyngeal secretions and imaging.19, 20 M. pneumoniae infection is defined as single titers of serum M. pneumoniae antibody ≥ 1:320, or single titers of serum M. pneumoniae antibody ≥ 1:160 with positive PCR of M. pneumoniae or seroconversion (antibody titer increase of ≥ 4 fold between paired sera). Sputum smear and culture of bacteria and fungi, tuberculin skin test and interferon‐gamma release assay (when necessary) are performed before using antibiotics to exclude other pathogen specific pneumonia. Indirect immunofluorescence assays (Diagnostic Hybrids, Ohio, USA) to detect respiratory syncytial viruses (RSV), influenza viruses (A and B), parainfluenza viruses (1, 2, 3) and adenoviruses (ADV) antigens are performed using nasopharyngeal swabs. Detailed inclusion and exclusion criteria are shown in Table 2.

Table 2

Inclusion and exclusion criteria

Inclusion criteria: fulfill all of the followings

1. Less than 18 years old

2. Severe pneumonia that is defined as pneumonia with one of the followings:

◊ poor general condition

◊ increased respiratory rate(infant>70/min, older children>50/min)

◊ dyspnea

◊ cyanosis

◊ multilobe involvement or > 2/3 lung involvement

◊ extrapulmonary complication

◊ pleural effusion

◊ Transcutaneous oxygen saturation in room air <92%

3.Serum M. pneumoniae antibody ≥ 1:320, or serum M. pneumoniae antibody ≥ 1:160 with positive PCR of M. pneumoniae or seroconversion (increased antibody titers (≥4 folds)

Exclusion criteria: if fulfilling any of the followings will be excluded

◊ Evidence of other pathogen specific (bacterial, viral, fungal, tuberculosis) pneumonia

◊ Respiratory failure requiring mechanical ventilation

◊ Liver failure or renal insufficiency or heart failure

◊ Other system diseases: congenital heart disease, kidney disease, connective tissue disease, immunodeficiency, tumor, hypertension, diabetes mellitus or hemophagocytic syndrome

◊ Recurrent respiratory tract infection

◊ Congenital bronchopulmonary dysplasia

◊ Increased intraocular pressure

◊ History of continuous use of glucocorticosteroid ≥ 1 week in previous 3 months

◊ Having contraindications to glucocorticosteroids or azithromycin

◊ Using of immunosuppressant before randomization

◊ Undergoing trial for other medications or instruments in the last 3 months.

Interventions and follow‐up

Eligible patients are centrally randomized into two groups. Patients in the low‐dose group receive 2 mg/kg/d (≤60 mg/d) intravenous methylprednisolone for 3 days followed by tapering over 12 days (Table 3). If the patient's temperature is more than 38°C 12 to 24 h after treatment is initiated, methylprednisolone is adjusted to 4 mg/kg/d at day 2 for 3 days, followed by tapering over 12 days. Patients in the high‐dose group receive 10 mg/kg/d (≤300 mg/d) intravenous methylprednisolone for 3 days followed by tapering over 12 days (Table 3). When methylprednisolone is reduced to 10–20 mg/d, patients can change to an oral formula and be discharged if necessary. Basic treatment with azithromycin is used in both groups following previously published guidelines.19, 20

Table 3

Randomized assigned interventions of methylprednisolone

Time of treatment	Group
	Low‐dose group (mg/kg/d)	High‐dose group (mg/kg/d)
Day 1	2	10
Day 2	2	10
Day 3	2	10
Day 4	1	1
Day 5	1	1
Day 6	1	1
Day 7	0.5	0.5
Day 8	0.5	0.5
Day 9	0.5	0.5
Day 10	0.25	0.25
Day 11	0.25	0.25
Day 12	0.25	0.25

After discharge, patients in both groups are followed‐up at 1‐month, 3‐months and 6‐months. Items to be monitored at follow‐up include clinical manifestations and adverse events such as hyperglycemia, hypertension and intraocular pressure. Assessment of pulmonary lesions, including atelectasis, bronchiectasis and bronchiolitis obliterans will be evaluated at the 6‐month follow‐up. If the patients do not recover after 6 months, follow‐up will be continued until the patient completely recovers or 1 year after treatment.

Randomization and blinding

The randomization code list is generated centrally by the Center for Clinical Epidemiology and Evidence‐based Medicine, Beijing Children's Hospital. Patients who meet criteria for enrollment are randomized (1:1) into two treatment groups. The procedure for randomized allocation includes: identification of participant by name, identification number and center series number, allocation of a random number to a medical center using an interactive voice response system, specification of a drug administration procedure for each participant. After consent and prior to randomization, site staff register each recruit on a web‐based electronic data capture system. Each recruit is assigned a unique study patient identification number by the system. After assignment of the randomization code, researchers are un‐blinded to the treatment dosage of methylprednisolone while the patients and data analyst are blinded to treatment groups.

Study outcomes

The primary composite outcome is the incidence of atelectasis, bronchiectasis or bronchiolitis obliterans at the 6‐month follow‐up. The outcome is measured independently by two radiologists. Atelectasis is defined as collapse of alveolar spaces with segmental or lobe volume decrease. Radiologic manifestations might show consolidation of the alveolar cavity and compensating emphysema of other lung tissues. Bronchiectasis is a structural abnormality characterized by abnormal dilation and distortion of the bronchial tree. Chest computerized axial tomography (CT) scan shows dilated and thickened airways, including tram or parallel lines and ring shadows on cross section. Bronchiolitis obliterans is a disease that results in obstruction of the smallest airways of the lungs due to inflammation. It is defined as expiratory air trapping (mosaic or diffuse) and bronchial wall thickening on high‐resolution CT and obstructive changes with air trapping, but without reversibility following inhaled bronchodilator of pulmonary function test.

Secondary outcomes include recovery time of the patient's temperature, proportion of pulmonary lesions absorbed, changes of mucosa identified by bronchoscopy, length of hospital stay, number of participant(s) needing intensive care, number of participant(s) with acute respiratory distress syndrome, hemophagocytic syndrome, death, or any adverse event/severe adverse event (eg. hyperglycemia, hypertension) during the trial and pulmonary function at the 6‐month follow‐up.

Study Data

Demographic information is recorded on standardized case report forms (CRF) at baseline. Clinical and laboratory data are obtained at baseline and every planed time point after initiation of treatment. During follow‐up, the physical status and imaging examination data are recorded on CRFs. The details of data collection for the study are described in Table 4. All laboratories of the participating centers are internationally validated and standardized. In different phases of the trial, specific lab tests will be done as appropriate for disease condition, which will be determined the pediatrician and noted on the CRF. Using double data entry with an adjudication process, completed forms are reviewed and data are entered into electronic CRFs (eCRFs). Trial monitoring (including trial safety, protocol adherence and data quality) and reporting of adverse events are conducted under the supervision of the trial's medical monitor. All subjects are to be questioned regarding adverse events during treatment at each visit. All reported adverse events will be analyzed regardless of the investigators assessments of causality.

Table 4

Study schedule of clinical trial (6 months)

Items	Study visit/trial phases
	Baseline assessment	Treatment				Follow‐up
	Day 0	Day 1	Day 2	Day 3‐12	Discharged day	1 month ± 7 days	3 months ± 7 days	6 months ± 7 days	Post‐Hnal visit
Consent	X
Demographic information	X
Medical history	X					X	X	X	X
Manifestation and plnsieal examination	X	X	X	X	X	X	X	X	X
X‐ray				X
Chest CT	X							X
Laboratory test†	X				X	X	X	X	X
Pathogen test‡	X
Blood pressure	X	X	X	X	X	X	X	X	X
Blood glucose	X	X	X	X	X			X
Tuberculin lest	X
Fundus and intraocular pressure exam	X				X	X	X	X	X
Bone Density Measurement	X				X	X	X	X	X
Lung function test	X					X	X	X	X
ECG	X				X
Bronchoscope§			X
Methylprednisolone		X	X	X
Modify the dose in the low‐dose group¶			X
Adverse event/Severe adverse event		X	X	X	X	X	X	X	X

† Laboratory tests include blood gas analysis, blood biochemical indexes (including electrolytes, liver, renal and cardiac function), whole blood cell analysis, C‐reactive protein (CRP), procalcitonin (PCT), erythrocyte sedimentation rate (ESR), coagulation function (including D‐Dimer), serum ferritin (SF), immune function test; whether or not to check is according to the patient's condition in different visit time. During the follow up, if the results are normal, no further laboratory tests will be necessary. ‡ Pathogen tests include Mycoplasma pneumoniae antibody, PCR of Mycoplasma pneumoniae of nasopharyngeal swab, smear and culture of bacteria and fungi of sputum, tuberculin skin test, interferon‐gamma release assay (when necessary) and nasopharyngeal swab for virus antigen. § Bronchoscope will be done according to the patient's condition. ¶ Modify the dose in the low‐dose group means, if the temperature is more than 38°C after 12 hours to 24 hours of initiated treatment, the participants will receive methylprednisolone 4 mg/kg/d at day 2 for 3 days followed by tapering over 14 days.

Sample size and statistical analysis

The sample size for this two‐arm trial was calculated on the basis of the comparison of low‐ versus high‐dose methylprednisolone treatment. Using the data from our previous pilot study, we assumed a rate of pulmonary outcomes of 50% in the low‐dose methylprednisolone group and 35% in the high‐dose methylprednisolone group. To achieve a statistical power of 80% (two‐sided type 1 error of 5%), the calculated sample size of each treatment group was 167 patients per treatment group (334 in total). Considering an expected loss to follow‐up of at least 20%, 201 patients per treatment group (402 in total) were required.

The primary composite outcomes of the low‐ and high‐dose methylprednisolone groups at the 6‐month follow‐up will be compared by Chi‐square test with two‐sided tests at the 5% level of significance. Efficacy of the two groups will be assessed using the relative risk, number needed to treat and 95% CI (confidential interval). The occurrence of long‐term pulmonary outcomes during follow‐up will be described using a Kaplan‐Meier curve. Using this description, a COX proportional hazards model will be established.

DISCUSSION

MPP is mild or benign in most children worldwide. However, nearly 40% of children in China progress to severe MPP despite appropriate antibiotic treatment.4 Pediatric patients can present with complications such a s pleural effusion, multi‐organ d amage and long‐term pulmonary outcomes (bronchiolitis obliterans, bronchiectasis or atelectasis).7 Previous studies11, 12 have shown that adjuvant treatment with glucocorticoids was beneficial for alleviating respiratory symptoms and reducing levels of inflammatory factors in patients with severe or refractory MPP. However, the optimal dosage of glucocoricoids is not clear and has never been mentioned in clinical guidelines. In the clinic, routine dosage of methylprednisolone is usually 1–2 mg/kg/d for severe MPP, although outcomes still remain in some cases, especially in severe patients. A retrospective study21 with small case numbers showed that methylprednisolone pulse therapy was superior to low‐dose methylprednisolone in recovery time of patient temperature and proportion of pulmonary lesion absorption. To date, prospective RCTs to compare the benefits and safety of low‐ and high‐dose glucocorticoid treatment for children with severe MPP have not been conducted. Previous studies13, 14, 15, 16 often used recent curative effect index, including length of stay, recovery time of patient temperature or inflammatory marker(s) to evaluate the benefits of glucocorticoids. These studies did not use a long‐term outcome index. Our MCMP trial is the first study designed to evaluate the benefits and safety of low‐ and high‐dose glucocorticoid treatment for reducing long‐term pulmonary outcomes in patients with severe MPP. We chose the percentage of atelectasis, bronchiectasis or bronchiolitis obliterans at the 6‐month follow‐up as primary outcome measures to assess the long‐term effect of methylprednisolone treatment. Patients are only enrolled if they meet our stringent inclusion criteria for severe MPP, this ensures the rate of pulmonary outcomes will be high in our study.

There are many available glucocorticoids, including hydrocortisone, dexamethasone, methylprednisolone, prednisolone and prednisone; currently, the appropriate choice of glucocorticoid for treatment is debatable. Previous studies reported that methylprednisolone, a median‐effect drug, had a powerful anti‐inflammatory function and was often used in patients with severe pneumonia.22, 23, 24, 25 Taking this into account, we decided to use methylprednisolone for treatment in our study. H ydrocortisone is a natural glucocorticoid with a short‐term effect, often used in critically ill patients in combination with a mineral corticoid.26 There is little research to support the use of dexamethasone in patients with severe MPP, aside from a report in 2011,27 likely because of its strong side effects on the pituitary body and adrenal cortex. Prednisone is only available as an oral formula and cannot be used in patients with severe liver insufficiency, making methylprednisolone preferred.

A previous study28 showed that high‐dose and long‐term use of glucocorticoids in the treatment of severe sepsis and septic shock can cause co‐ and re‐infections, hyperglycemia or even excess mortality in adults. Accordingly, our RCT evaluates the adverse effects of both low‐ and high‐dose methylprednisolone by monitoring blood glucose, blood pressure and intraocular pressure both when the patients are in the hospital and after discharge, with follow‐up at 1‐, 3‐, and 6‐months after completion of treatment. Bone et al28 recommended tapering of the glucocorticoid dosing to avoid a rebound of inflammatory markers. Thus, we included tapering of methylprednisolone dosing in our study. Another study29 showed that if glucocorticoids were given for more than seven days in a row, the risk of side effects would increase, while a shorter course of glucocorticoids may not improve the primary outcome. Therefore, we have limited the use of methylprednisolone to 12 days in our study.

The macrolide‐resistance rate of M. pneumoniae was reported to be higher in China than in other countries, with a resistance rate of over 90%.30, 31 However, our previous study31 showed there was no significant difference in treatment response to azithromycin between the macrolide‐resistant and macrolide‐sensitive groups other than duration of fever, which is in line with the results of a study by Suzuki et al.32 This may contribute to the difference between in vitro and in vivo studies. Although tetracyclines and quinolones are effective antibiotics for treatment of macrolide‐resistant M. pneumonia, they are not recommended for children under 8 or 12 years old, respectively, because of potential dental enamel damage and bone toxicity. Azithromycin is the first line antibiotic choice for MPP. In our study, azithromycin is used as the basic treatment in both study groups.

In conclusion, this large and adequately powered randomized trial is expected to determine the efficacy and safety of low‐ and high‐dose methylprednisolone treatment combined with azithromycin for reducing long‐term pulmonary outcomes in pediatric patients with severe MPP. This RCT addresses a large knowledge gap in an under‐researched area. The results of this trial will provide scientific evidence to guide clinical practice in the treatment of severe MPP in pediatric patients.

Our study has several limitations. First, we are only studying hospitalized children with severe MPP, so the benefit of methylprednisolone in CAP caused by other pathogens is not evaluated. Second, methylprednisolone is the only glucocorticoid used to treat severe MPP in our study, and effects of other glucocorticoids are not evaluated. Finally, our study data are from Chinese pediatric patients, limiting the generalizability to non‐Chinese populations. Additional studies will be needed to verify the results of our study.

CONFLICT OF INTEREST

The authors declare that they have no competing interests.