Zinc supplementation as an adjunct to standard therapy in childhood nephrotic syndrome - a systematic review

Table 1 Characteristics of included studies

Ref.	Setting, country	Participants	Intervention	Outcomes measured	Comments
Arun et al[5]	Hospital (out-patient), India	Number: 81 [Frequent relapse = 52 (zinc = 26; placebo = 26); Infrequent relapse = 29 (zinc = 14; placebo = 15)] Age: 1-16 yr Inclusion: SSNS with infrequent relapses or FRNS with prednisolone requirement ≤ 0.75 mg/kg on alternate days	Dose: Zinc sulfate 10 mg/d (1 h before or 2 h after meal) Duration: 12 mo	Frequency of relapses, number of relapses (mean), time to first relapse, adverse drug affects, proportion of infection associated relapses, and change in serum zinc level	Double blind placebo-controlled trial. ITT analysis not done. Small sample size (underpowered to show significant differences in the groups). Inclusion of infrequent relapsers may have diluted the significance of the findings. Authors proposed testing of a higher zinc dose along with immunological correlation
Sherali et al[12]	Hospital (out-patient), Pakistan	Number: 60 (zinc = 30; placebo = 30) Age: 2-15 yr Inclusion: FRNS	Dose: Zinc sulfate 10 mg/d Duration: 6 mo	Frequency of relapses, number of relapses (mean), episodes of infections, adverse drug affects, and change in serum zinc level	Double blind placebo-controlled trial. ITT analysis not done. Small sample size. Allocation concealment not clear. Post-supplementation zinc level was not measured in all subjects. Authors proposed testing of a higher zinc dose in a larger cohort
Afzal et al[18]	Hospital (out-patient), India	Number: 30 (zinc = 16; placebo = 14) Age (mean ± SD): 6.45 ± 2.92 yr Inclusion: FRNS (n = 24) and SDNS	Dose: Zinc 20 mg/d Duration: 2 wk starting at the onset of an episode of infection (for 12 mo)	Frequency of relapses, number of relapses (mean), episodes of infections, adverse drug affects, and change in serum and hair zinc level	Open label trial. ITT analysis not clear. Small sample size. Post-supplementation. Authors proposed testing of a higher zinc dose in a larger population
Pardillo et al[19]	Hospital (out-patient), Philippines	Number: 34 Age: Not clear (only children included) Inclusion: SSNS (majority) and SDNS	Dose: RDA Duration: 6 mo	Frequency of relapses, number of relapses (mean), episodes of infections, and adverse drug affects	Double blind placebo-controlled trial. ITT analysis not clear. Small sample size. Authors proposed testing of a higher zinc dose in a larger population

SSNS: Steroid sensitive nephrotic syndrome; FRNS: Frequently relapsing nephrotic syndrome; SDNS: Steroid dependent nephrotic syndrome; ITT: Intention-to-treat analysis; SD: Standard deviation; RDA: Recommended daily allowance.