The dangers of non-randomized, observational studies: experience from the COVID-19 epidemic

Nirmatrelvir/ritonavir for COVID-19: an overview of systematic reviews

OBJECTIVES

A reappraisal of the validity of the conclusions of systematic reviews (SRs) related to nirmatrelvir/ritonavir for the treatment of COVID-19.

METHODS

An overview of SRs (umbrella review). The methodological quality of the SRs was assessed using the AMSTAR 2 checklist; quality of the evidence from the trials included in each SR was appraised following the GRADE approach.

RESULTS

Sixteen SRs with meta-analysis published between 2020 and 2023 were included in this overview. The SRs reported data from 108 overlapping reports, based on 43 individual primary studies [3 randomized clinical trials (RCTs), 40 non-RCTs]. In outpatient settings the use of nirmatrelvir/ritonavir reduced overall mortality, hospital admission and progression of disease compared with controls (from moderate to low certainty of evidence); nirmatrelvir/ritonavir reduced mortality, hospital admission and progression of disease in both immunized and non-immunized patients. No differences in the occurrence of any adverse events between groups were observed in the large majority of SRs; serious adverse events, including adverse events requiring discontinuation of treatment, were reported with lower prevalence in nirmatrelvir recipients compared with controls (from low to moderate certainty of evidence).

CONCLUSIONS

There is low to moderate certainty of evidence from SRs that nirmatrelvir/ritonavir reduces mortality, clinical progression and hospitalization rate in COVID-19 patients compared with controls, without increasing the occurrence of overall and serious adverse events. Based on the overall methodological assessment, on average we can have high confidence in the quality of results generated by the SRs.

Role of FXR in Renal Physiology and Kidney Diseases

Farnesoid X receptor, also known as the bile acid receptor, belongs to the nuclear receptor (NR) superfamily of ligand-regulated transcription factors, which performs its functions by regulating the transcription of target genes. FXR is highly expressed in the liver, small intestine, kidney and adrenal gland, maintaining homeostasis of bile acid, glucose and lipids by regulating a diverse array of target genes. It also participates in several pathophysiological processes, such as inflammation, immune responses and fibrosis. The kidney is a key organ that manages water and solute homeostasis for the whole body, and kidney injury or dysfunction is associated with high morbidity and mortality. In the kidney, FXR plays an important role in renal water reabsorption and is thought to perform protective functions in acute kidney disease and chronic kidney disease, especially diabetic kidney disease. In this review, we summarize the recent advances in the understanding of the physiological and pathophysiological function of FXR in the kidney.