Single vs split dose of prednisolone in the treatment of relapses of childhood nephrotic syndrome

Nephrotic syndrome is the commonest glomerular disease in childhood. It usually follows a relapsing and remitting course. Corticosteroids are the mainstay of treatment for both the first episode and subsequent relapses. This study was conducted at a single centre to compare the clinical response to a single dose vs. split dose of prednisolone in the treatment of relapses of childhood nephrotic syndrome. Children between the ages of 1 and 14 years admitted with a relapse of idiopathic steroid sensitive nephrotic syndrome from August 2019 to February 2020 were considered for recruitment. A block randomization method based on age was used for allocation. Patients randomised to group A received oral prednisolone at 60 mg/m2 as a single morning dose, while those randomised to group B received the same total dose as two divided doses, of which 2/3 was given in the morning and the rest in the evening. Treatment was continued until remission was achieved following which all patients were switched to alternate day prednisolone. An independent sample t test was used to compare the two groups. One hundred and four episodes of relapse occurring in 96 children were included of which 49 were treated with prednisolone as a split dose and 55 were treated with a single dose of prednisolone. The mean duration to achieve remission for the split-dose group was 8.02 days (SD 1.58) while it was 9.74 days (SD 3.72) for the single-dose group. This difference was statistically highly significant (t(102) = 3.004; p = 0.001; CI 0.58 to 2.86). There was no difference in the adverse events profile of the two groups. Conclusion: The use of prednisolone as a split dose results in a shorter duration to achieve remission when compared to a single morning dose, resulting in a lower cumulative dose of prednisolone to achieve remission. What is Known: • Corticosteroids are the mainstay of treatment for childhood nephrotic syndrome. • Corticosteroids are given as a single dose in the morning to minimise adrenocortical suppression. What is New: • A more rapid attainment of remission can be achieved with a split dose of corticosteroids. What is Known: • Corticosteroids are the mainstay of treatment for childhood nephrotic syndrome. • Corticosteroids are given as a single dose in the morning to minimise adrenocortical suppression. What is New: • A more rapid attainment of remission can be achieved with a split dose of corticosteroids.


Introduction
Nephrotic syndrome is the commonest glomerular disease in childhood. It usually follows a relapsing and remitting course. The exact aetiology remains uncertain, though evidence suggests an immunological origin with abnormalities in T cell function postulated [1,2]. Corticosteroids are the mainstay of treatment for both the first episode and subsequent relapses.
Glucocorticoids have pleiotropic effects that are used to treat diverse diseases such as nephrotic syndrome, asthma, rheumatoid arthritis and systemic lupus erythematosus. They are also part of most post transplantation immunosuppression protocols. Prednisolone is the most commonly used corticosteroid in nephrotic syndrome with a plasma half-life of 2 to 4 h. It has good oral bioavailability and is eliminated mainly by hepatic metabolism and renal excretion of the metabolites. These metabolites are excreted in the urine as free and conjugated metabolites together with an appreciable Communicated by Peter de Winter.
proportion of unchanged prednisolone. Plasma concentrations follow a biexponential pattern. The short elimination half-life of prednisolone dictates that daily dosing, which is usually given in the morning, cannot achieve steady-state plasma levels, and is likely to be exerting little or no effect in the second half of the day [3].
The treatment of childhood nephrotic syndrome has been governed by recommendations made by the International Study for Kidney Diseases in Children (ISKDC) and the Arbeitsgemeinschaft fur Paediatrische Nephrologie (APN) [4][5][6]. In the ISKDC regimen, prednisone was given at 60 mg/m 2 /day (maximum dose 80 mg/day) in divided doses for 4 weeks, followed by 40 mg/m 2 /day (maximum dosage 60 mg/day) in divided doses, three consecutive days out of seven (intermittent dosing), for 4 weeks for the first episode while a relapse was treated with prednisone given at 60 mg/ m 2 /day in divided doses till remission, followed by 40 mg/ m 2 /day in divided doses, three consecutive days out of seven, for 4 weeks. The APN study compared the intermittent dosing regimen of the ISKDC with an alternate day dosing regimen and found the latter to be significantly more efficacious in reducing the relapse rate. Both these studies utilized a divided daily dose of prednisolone.
Based on these recommendations, the modified ISKDC regimen was formulated. Accordingly, oral prednisolone, prescribed at a dose of 60 mg/m 2 for 4 weeks, followed by 40 mg/m 2 every other day (EOD) for a further 4 weeks, remained the standard therapy for around a quarter of a century. Many units preferred utilisation of prednisolone as a single daily dose as opposed to the divided dose regime used in the original protocol. The preference to use a single daily dose given in the morning is based on the desire to reduce the adverse effect profile, minimize suppression of the adrenocortical axis [7] and to achieve better compliance [8].
Patients with nephrotic syndrome in relapse are at risk of major complications such as acute kidney injury due to hypovolaemia, sepsis and vascular thrombosis. It ensues that patients would benefit from rapid attainment of remission in order to minimise such complications. Furthermore, treatment of a relapse of nephrotic syndrome requires high dose prednisolone at 60 mg/m 2 until remission is achieved, with the potential for steroid toxicity. If remission is achieved early, the ultimate steroid burden during a relapse would be less, thus potentially reducing steroid toxicity.
We have observed in our patient population that children who have not shown an initial response with single dose prednisolone responded to a divided dose regimen given as twothirds of the dose in the morning and the rest in the evening. This might be due to the presence of persistently high levels of steroids within the circulation throughout the day. This split-dose regimen may potentially increase the risk of steroid toxicity through persistently elevated steroid levels. However, if remission is achieved earlier, the ultimate cumulative dose of steroids required to achieve remission would be less, thus reducing steroid burden and thereby steroid toxicity.
In this study, we compare the clinical response to a single dose vs. split dose of prednisolone in the treatment of relapses of childhood nephrotic syndrome.

Patients and methods
This study was conducted at the paediatric nephrology section of the Professorial Paediatric Unit at Teaching Hospital Peradeniya, Sri Lanka, which is a tertiary referral centre. Children between the ages of 1 and 14 years admitted to the unit from September 2019 to February 2020 due to a relapse of idiopathic steroid sensitive nephrotic syndrome were considered for recruitment to the study. A relapse was defined as 3 + proteinuria for three consecutive days with hypo-albuminaemia (< 25 g/l) and hyper-cholesterolaemia. All patients had their blood tested for serum albumin, serum cholesterol and serum creatinine and a urinalysis performed for protein, sugar and cells on admission to the ward. Patients who had been started on treatment for relapse prior to admission, patients with deranged renal functions, patients not fulfilling criteria for a relapse and those with other associated co-morbidities were excluded. Informed written consent was obtained from the parents of all subjects included in the study.
During the period of study, there were 123 episodes of relapse of which 104 were selected according to the inclusion and exclusion criteria.
The enrolled subjects were grouped and randomised according to a computer-generated system. Patients randomised to group A were given oral prednisolone at 60 mg/m 2 (dose rounded off to the nearest 5 mg) as a single morning dose, while those in group B were given the same total dose as two divided doses, of which 2/3 was given in the morning and the rest in the evening (all doses rounded up to the nearest 5 mg). The reason to give a higher dose in the morning was to minimise effects on the adrenocortical axis by keeping to the native pattern of steroid release while ensuring that a sufficient dose was given in the evening to maintain steady-state concentrations. The decision to give 2/3 of the dose in the morning and one-third in the evening was therefore made, and this was in keeping with the practice used in the unit. This regimen was continued until remission was achieved (nil or trace proteinuria for 3 consecutive days) following which all patients were switched to alternate day prednisolone at 60 mg/m 2 which was given as a single morning dose in accordance with the unit protocol. The time taken from institution of therapy until remission was achieved was documented in all patients. The adverse event profile encountered by the patients was assessed using a questionnaire as well as examination and investigation findings, and the adverse events assessed were mood and behavioural changes, dyspeptic symptoms, increased appetite, new onset hypertension, altered blood sugar control and sepsis. Ethical approval for the study was obtained from the Scientific and Ethics Committee, Faculty of Medicine, University of Peradeniya, Sri Lanka, and the study was conducted in accordance with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. The study has been registered under clinical trial registry-registration number SLCTR/2019/025. (When searching for this study please use the title 'Single vs split dose of prednisolone in the treatment relapses of childhood nephrotic syndrome' (Fig. 1).

Data management and analysis
Out of 123 episodes of relapse, 104 (84.55%) were included in the clinical trial. Reasons for exclusion are given in Table 1. Randomisation was done using computer-based block randomization. Data was entered in to SPSS version 25, and descriptive data was presented using means with standard deviations.
Both descriptive and inferential statistics were utilised according to the objective of the study. Descriptive statistics were used to identify and compare the baseline characteristics of the two groups; single dose and split dose. Independent sample t test was used to compare the clinical response to single dose vs split dose of prednisolone in patients with childhood nephrotic syndrome presenting in relapse, based on the number of days taken to achieve remission.

Results
Of the 104 episodes of relapse of steroid sensitive nephrotic syndrome included in the study, 55 were treated with a single early morning dose of prednisolone and 49 received prednisolone as a split dose. A comparison of baseline characteristics of the two study groups (single dose vs split dose) is shown in Table 2.
The majority of the participants in both study groups were on alternate day prednisolone and/or other second line agents at the time of the relapse: 43 (78.2%) and 34 (69.4%) from the single dose and the split dose groups, respectively. The biochemical parameters of the subjects were also compared in the two study groups (Table 3). No significant differences were observed in urine albumin, serum albumin and serum cholesterol levels of the two study groups.
The primary objective of this study was to compare the clinical response to single dose vs. split dose of prednisolone in patients with childhood nephrotic syndrome in relapse. The clinical response was assessed by the number of days taken to achieve remission from the commencement of treatment. Figure 2 shows the variability of the number of days taken to achieve remission according to the type of treatment regimen.
In the two groups, the minimum number of days taken to achieve remission was 05 and 04 in the split dose and the single dose group respectively. The maximum number of days taken to achieve remission was 12 and 19 in the split and single dose groups respectively.
The average number of days taken to achieve remission was estimated for patients on single dose and split dose. The summary statistics of the average number of days taken to achieve remission for both groups is given in Table 4.
The independent sample t test revealed a significant difference between the two groups, t(102) = 3.004, p = < 0.001 (< 0.05) indicating that the average number days taken to achieve remission for the single dose group was significantly higher than the average number days taken to achieve remission for the split dose group.  The number of days taken to achieve remission was compared within the different age categories: age between 1 and 5, 5 and 10 and 10 and 14. The summary statistics were computed, and the results are given in Table 5.
This revealed a statistically significant difference in the 1-5year age group (p = 0.001) and 10-14 age group (p = < 0.001) between the two study groups with the split dose group taking a shorter duration of time to attain remission (Fig. 3).
The adverse events encountered included alterations in mood and behaviour, dyspeptic symptoms and increased appetite. There was no significant difference in these adverse events between the two groups. Other significant adverse events like new onset hypertension, altered blood sugar control and sepsis were not encountered in either group (Table 6).

Discussion
The treatment of childhood nephrotic syndrome worldwide is governed to a great extent by two protocols proposed by the International Study of Kidney Diseases in Children (ISKDC) and Arbeitsgemeinschaft fur Paediatrische Nephrologie (APN). Both these protocols recommend treatment of relapses with prednisone administered in three divided doses until remission is achieved. Thereafter, prednisone is administered intermittently on three consecutive days of the week according to the former, or on alternate days according to the latter for a further 4 weeks.
Subsequent to these recommendations, several studies have shown equal efficacy in the attainment of remission with the use of a single dose of prednisolone given in the morning. Warshaw and Hymes used a single daily dose of 2 mg/kg of prednisolone on 32 patients and found that the time taken to achieve remission was similar to the ISKDC regimen [9]. Choonara et al. in their study successfully treated almost all patients with a single daily dose prednisolone given as 30 mg/m 2 [10]. Lee and Lee also revealed similar efficacy with a single daily dose of prednisolone and also reported less adrenocortical suppression and fewer adverse events [4].
Ekka et al. in a prospective randomised control trial in 1997 that looked at a single dose (2 mg/kg) versus three divided dose regimen of prednisolone therapy for relapses     Based on our study, the use of prednisolone as a split dose results in earlier attainment of remission when compared to the same dose used as single dose in the morning. The fact that this was achieved with no increase in the adverse events profile is also of importance ( Table 6). The increased efficacy of prednisolone when used as a split dose can probably be explained by the fact that this dosing regimen achieves a steadier-state plasma concentration. We used a higher dose in the morning (2/3) in order to minimise adrenocortical suppression while still assuring high steady-state concentrations. No clinical evidence of adrenocortical suppression was encountered though this was not objectively measured. The use of a higher dose in the morning in keeping with the natural pattern of corticosteroid release may have minimised adrenocortical suppression.
As patients with nephrotic syndrome in relapse are at risk of major complications such as acute kidney injury due to hypovolaemia, sepsis and vascular thrombosis, a rapid attainment of remission would serve to minimize such complications, significantly reducing morbidity [11]. Furthermore, as treatment of a relapse of nephrotic syndrome requires treatment with high dose prednisolone, earlier attainment of remission would reduce the ultimate steroid burden and thereby steroid toxicity [12]. As all dosing was standardised based on the body surface area, we believe that the duration of steroid therapy correlates well with Fig. 3 Number of days taken to achieve remission by type of treatment regimen and by age group the cumulative dose of prednisolone the patient actually received. Therefore, the split-dose regime, through reducing the duration of a relapse, reduces both the potential for relapse-related complications as well as the steroid burden, during a relapse.
There are a number of methodological issues which were encountered during the analysis and interpretation of results. There were some differences in baseline characteristic between the two groups, especially with regard to second line agents, which may have effects on remission induction. Adrenocortical suppression was also not objectively measured. Furthermore, comparison of a larger group would help enhance the results of the sub group analysis.

Conclusion
This randomised controlled clinical trial revealed a more rapid attainment of remission with a split dose of prednisolone when compared with a single daily dose, in the treatment of relapses of childhood nephrotic syndrome, with no difference in the adverse event profile. Rapid attainment of remission has the benefit of reducing the cumulative steroid dose used to achieve remission as well as minimising the complications associated with a relapse by reducing the duration of relapse.
Authors' contributions All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Dr. W A L K Weerasooriya, Prof. R S Thalgahagoda and Prof. A S Abeyagunawardana. The first draft of the manuscript was written by Dr. W A L K Weerasooriya, and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Data availability
The data is available on request. However as patient confidentiality issues may arise prior approval from the Scientific and Ethics Committee, Faculty of Medicine, University of Peradeniya, Sri Lanka will need to be obtained before release.

Declarations
Ethics approval This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Ethics Committee of University Peradeniya, Sri Lanka (date 10/05/20019/ NO-2018/EC/26).

Consent to participate
Informed consent was obtained from parents or guardians of all individual participants included in the study.

Conflict of interest
The authors declare no competing interests.