# Variation in Attitudes to Native Kidney Biopsy Practice in the United States

## TL;DR

A survey of US kidney specialists found significant variation in attitudes toward kidney biopsies, influenced by factors like age, gender, and state characteristics.

## Contribution

The study identifies clinician and geographic factors influencing kidney biopsy recommendations in the US using a nationwide survey.

## Key findings

- Higher biopsy propensity scores were found in male, younger, and more experienced clinicians.
- US states with higher nephrologist density and lower deprivation had higher biopsy recommendation scores.
- There was significant variation in biopsy attitudes between US states, with scores ranging from 20.3 to 29.2.

## Abstract

There is substantial variation in kidney biopsy practices within and between countries; however, the reasons for this are unclear due to limited research among large diverse populations. The aim of this study was to explore variations in attitude to the indications and contraindications for native kidney biopsy in the United States (US).

A case-vignette questionnaire was developed. A propensity-to-biopsy score (0-44) was generated from responses to indications and contraindications, with a higher score indicating an increased likelihood to recommend biopsy. Dissemination of the questionnaire occurred by email, social media, and the National Kidney Foundation.

A total of 295 nephrologists/fellows from 43 states within the US participated.

All participants completed an identical questionnaire on kidney biopsy practice.

Responses were collected on indications, contraindications, and attitudes to biopsy.

Anonymized IP addresses were collected for comparison between US states. Data were also collected on the demographics of the individual and the type of institution in which the doctor was based.

In an adjusted multiple linear regression analysis, higher propensity-to-biopsy scores were demonstrated in US clinicians who were male, younger and more frequent performers of kidney biopsy (P = 0.05). There were significant differences between the 18 US states with 5 or more participants (P < 0.001) with the mean propensity-to-biopsy score ranging from 20.3 (Wisconsin) to 29.2 (New Jersey and Virginia). Increased biopsy propensity was also observed in US states with higher nephrologist density and lower statewide deprivation (P = 0.006).

The condensed clinical scenarios may not accurately replicate real-world cases, and clinicians opted in often using social media, so generalizability is limited.

Attitudes to kidney biopsy practice in the US are highly variable, and clinician or institutional characteristics do not fully explain these discrepancies. Further research is required to understand the factors that influence clinical decision making.

A kidney biopsy can be used to diagnose particular types of kidney disease; however, it exposes patients to a small risk of serious bleeding. A questionnaire was completed by kidney specialist doctors in the United States to determine when this test is best used. There were significant differences in attitudes between these doctors based on their sex, age, and state. States with less poverty and more specialist doctors were shown to have greater willingness to recommend biopsy. Doctors surveyed in the United States were more likely to recommend biopsy than doctors in the United Kingdom. The study is limited, as it does not measure real-world practice, and study participants were not reflective of the whole profession.