Abstract: Ten studies enrolling 630 participants were included. Overall, the quality of evidence was suboptimal due to the small number of included studies enrolling small numbers of participants; short follow-up in each study; only a few studies in each comparison category; and major concerns with methodological bias. Four studies (293 participants) contributed to the comparison of TwHF versus non-TwHF. TwHF significantly increased complete remission (RR 1.46, 95% CI 1.18 to 1.80) and complete or partial remission (RR 1.26, 95% CI 1.10 to 1.44) without escalating the adverse events profile at the last follow-up (12 to 16 months). Four studies (223 participants) compared TwHF with prednisone. There were no statistically significant differences between complete remission, partial remission, and complete or partial remission. Two studies (114 participants) contributed to the comparison of TwHF versus cyclophosphamide (CPA) at the last follow-up (3 to 12 months). There were no statistically significant differences between complete, partial, or complete or partial remission. One study (46 participants) reported TwHF was associated with a significantly lower serum creatinine compared with CPA (MD -14.00 μmol/L, 95% CI -26.43 to -1.57). No serious adverse events of TwHF were observed. One study (37 participants) reported TwHF was associated with a significantly lower risk of psychosis when compared to prednisone (RR 0.11, 95% CI 0.01 to 0.75), and two studies showed a significantly lower risk of hair loss with TwHF when compared to CPA ((2 studies, 114 participants): RR 0.11, 95% CI 0.02 to 0.59). TwHF may have an add-on effect on remission in patients with primary NS. There was insufficient evidence to assess if TwHF was as effective as prednisone or CPA. More methodologically sound and sufficiently powered studies, with adequate follow-up would help to better inform management options for the use of TwHF for primary NS. TwHF should be further directly compared with other widely used immunosuppressive agents after the superiority over placebo or no treatment has been clearly established.

Plain-language summary: In this review we investigated the use of TwHF as an immunosuppressive therapy for patients with primary NS. We only considered two standardised TwHF extracts which have lower toxicity profiles and fewer adverse effects than other non-standardised preparations. We reviewed the evidence from 10 randomised studies enrolling 630 Chinese patients with primary NS. Of these, four studies (293 patients) reported that when TwHF was used there was a significantly increased number of patients achieving complete, and complete or partial remission without increasing adverse events. There were no significant differences in complete, partial, or complete or partial remission when TwHF was compared with prednisone in four studies (223 patients). There were also no significant differences in complete, partial, or complete or partial remission when TwHF was compared with CPA in two studies (114 patients). One study reported TwHF significantly improved kidney function (decreased serum creatinine) when compared with CPA. TwHF was associated with a lower risk of psychosis than prednisone; and there was less likelihood of hair loss when compared to CPA. The quality of evidence was poor; there were only 10 studies, enrolling a total of 630 patients; follow-up was short; the maximum number of studies included in a comparison was four; and we had major concerns over the quality of the included studies. TwHF may have an add-on effect on remission in patients with primary NS; however there is insufficient evidence to assess if TwHF is as effective as prednisone or CPA.