# The evolution of consultation practices with general practitioners and nephrologists for patients with chronic kidney disease before and after the COVID-19 pandemic in France

Juliette Piveteau, Sahar Bayat, Cécile Vigneau, Cécile Couchoud, Maxime Raffray

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## ► To cite this version:

Juliette Piveteau, Sahar Bayat, Cécile Vigneau, Cécile Couchoud, Maxime Raffray. The evolution of consultation practices with general practitioners and nephrologists for patients with chronic kidney disease before and after the COVID-19 pandemic in France. Journal of Nephrology, 2025, 38 (8), pp.2407-2416. 10.1007/s40620-025-02376-5. hal-05199570

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# The evolution of consultation practices with general practitioners and nephrologists for patients with chronic kidney disease before and after the COVID-19 pandemic in France

Juliette Piveteau<fnref n="1" /> · Sahar Bayat<fnref n="1" /> · Cécile Vigneau<fnref n="2" /> · Cécile Couchoud<fnref n="3" /> · Maxime Raffray<fnref n="4" />

Received: 22 January 2025 / Accepted: 12 July 2025

© The Author(s) 2025

## Abstract

**Background** The COVID-19 pandemic led to concerns about disruptions in the follow-up of chronic diseases, including chronic kidney disease (CKD). Here, we assessed the COVID-19 pandemic impact on healthcare use by patients with CKD in France.

**Methods** We used the French National Health Data System (SDNS) that contains data on outpatient and inpatient health-care of the whole French population. Using a validated algorithm, we identified two CKD cohorts based on their healthcare utilization: (i) the 2019 cohort (pandemic-exposed) and (ii) the 2017 cohort (comparator). We followed these cohorts for 2 years and compared consultations (in-person and teleconsultation) with a general practitioner (GP) and a nephrologist and all-cause hospitalizations (excluding COVID-19 as primary diagnosis). We stratified comparisons by age group and sex.

**Results** We identified 4,866,096 individuals with CKD in 2017 and 5,089,706 in 2019. During the first year of follow-up, 95.2% and 6.4% of patients in the 2017 cohort had at least one consultation with a GP and with a nephrologist, respectively, versus 94% and 6.3% in the 2019 cohort. Teleconsultations compensated for the reduction of in-person GP and nephrologist consultations throughout the lockdown periods in 2020 and 2021 (40.5% of patients in the 2019 cohort had at least one in-person consultation and 52.5% an in-person or tele-consultation with a GP). Hospitalizations ≥ 24 h decreased in 2020 and 2021 (-10%).

**Conclusions** In France, outpatient care for CKD was maintained during the 2 years following the COVID-19 pandemic, thanks to teleconsultations. The persistently lower inpatient care utilization warrants further investigation.

<figure><img src="image_3.png" /></figure>

<footnote>Maxime Raffray
maxime.raffray@ki.se</footnote>

<footnote n="1">¹ EHESP, CNRS, Inserm, Arènes-UMR 6051, RSMS, U1309, Univ Rennes, Rennes, France</footnote>

<footnote n="2">² Univ Rennes, CHU Rennes, INSERM, EHESP, IRSET (Institut de Recherche en Santé, Environnement et Travail)-UMR S 1085, Rennes, France</footnote>

<footnote n="3">³ Renal Epidemiology and Information Network (REIN) Registry, Biomedicine Agency, Saint-Denis-La-Plaine, France</footnote>

<footnote n="4">⁴ Division of Clinical Epidemiology, Department of Medicine Solna, Karolinska Institutet, Solna, Sweden</footnote>
**Graphical abstract**

# The evolution of consultation practices with general practitioners and nephrologists for patients with chronic kidney disease before and after the COVID-19 pandemic in France

Juliette Piveteau [1], Sahar Bayat [1], Cécile Vigneau [2], Cécile Couchoud [3], Maxime Raffray [4]

[1] EHESP, CNRS, Inserm, Arènes-UMR 6051, RSMS, U1309, Univ Rennes, Rennes, France [2] Univ Rennes, CHU Rennes, INSERM, EHESP, IRSET (Institut de Recherche en Santé, Environnement et Travail) - UMR S 1085, Rennes, France [3] Renal Epidemiology and Information Network (REIN) Registry, Biomedicine Agency, Saint-Denis-La-Plaine, France [4] Karolinska Institutet, Department of Medicine, Division of Clinical Epidemiology, Solna, Sweden

**Background**

The COVID-19 pandemic had a significant impact on individuals with chronic kidney disease (CKD), particularly in terms of mortality. Our aim was to assess the impact of the COVID-19 pandemic on the healthcare use of patients with CKD in France.

**Methods**

French National Health Data System (SNDS)

SNDS

Algorithm RENALGO

Cohort 2017

Cohort 2019

(unexposed) (exposed to COVID-19)

**Outcomes :**

- Consultation with general practitioner (GP) and nephrologist

- Hospitalization, all diagnoses

**Results**

**Description of the population**

<figure><img src="image_4.png" /></figure>

Cohort 2017

<figure><img src="image_5.png" /></figure>

N = 4 866 096

<figure><img src="image_6.png" /></figure>

62 years (mean)

<figure><img src="image_7.png" /></figure>

60% of women

<figure><img src="image_8.png" /></figure>

Cohort 2019

N = 5 089 706

63 years

59% of de women

**Main results**

- During the first year of follow-up, 95.2% and 6.4% of patients in the 2017 cohort had at least one consultation with a GP and with a nephrologist, respectively, versus 94% and 6.3% in the 2019 cohort.

- Teleconsultations compensated the deficit of in-person consultations with GP and nephrologists throughout the lockdown periods : 40.5% of patients in the 2019 cohort had at least one in-person consultation and 52.5% an in-person or tele-consultation with a GP

<figure><img src="image_9.png" /></figure>

Journal of NEPHROLOGY

<figure><img src="image_10.png" /></figure>

official journal of the Italian Society of Nephrology

**Conclusions**

The evidence of continuity of care brings a reassuring message to nephrologists and individuals with CKD.

**Keywords** COVID-19 · Chronic kidney disease · Healthcare utilization · Teleconsultation

**Introduction**

The coronavirus disease 2019 (COVID-19) led to the death of more than 7 million individuals worldwide as of September 2024 [1]. On March 12, 2020, after the confirmation of 118,000 cases of COVID-19 in 114 countries, including 4,291 deaths, the World Health Organization defined COVID-19 as a pandemic [2]. Besides the direct casualties, the pandemic greatly disrupted the functioning of many aspects of society, including healthcare service delivery [3]. Direct healthcare disruptions were reported early in the pandemic, such as reallocation of resources and discontinuation of emergency and acute care [4]. Additionally, countries deployed a range of policies to control the pandemic, including lockdowns [5]. This resulted in a global decrease in healthcare use [6], leading to concerns about its potential long-term negative consequences on the population health. Indeed, healthcare disruptions have been associated with subsequent preventable hospital admissions [7] and delays in the diagnosis and treatment of several non-communicable diseases, including cardiovascular diseases [8] and cancer [9].

Chronic Kidney Disease (CKD) is a silent disease that slowly progresses over months or years, with a prevalence of 10% in the adult population [10]. This disease is defined as “the presence of markers of kidney damage or a decrease in the estimated glomerular filtration rate below 60 ml/min/1.73 m² for more than three months, regardless of its cause” [11]. Early detection and close follow-up with adherence to care guidelines are crucial for better outcomes, including preventing or better anticipating kidney failure [12, 13]. In France, CKD patients should be co-managed by GP, nephrologist, and nurse practitioners, with follow-up frequency increasing as kidney function declines. Guidelines range from yearly GP visits at early stages to monthly visits alternating nephrologist, nurse practitioner and GP at stage 5 non-treated by kidney replacement therapy (KRT) [13].

Individuals with CKD are particularly vulnerable to COVID-19, with increased mortality [14–18]. Few studies have investigated the changes in healthcare use and potential disruptions specifically in individuals with non-dialysis-dependent CKD. A US study found a reduction in overall healthcare use during the early months of the pandemic followed by an incomplete rebound [19]. However, data are scare in countries with universal healthcare coverage. Our

<figure><img src="image_11.png" /></figure>
aim was to assess the impact of the COVID-19 pandemic on
the healthcare use of patients with CKD in France.

# Materials and methods

## Data sources

This observational retrospective study was carried out using
data from the French National Health Data System (SNDS).
The SNDS contains all inpatient and outpatient claims and
hospital discharges for 99.5% of the 67 million inhabitants of
France (i.e., beneficiaries of the universal healthcare cover-
age system). The data include information on reimbursed
drug deliveries and inpatient/outpatient medical procedures
and diagnoses. Some sociodemographic information on the
beneficiaries is also available, including age, sex and area
of residence [20].

## Study population

The study population was identified in the SNDS data for
2017 and for 2019 using the validated algorithm RENALGO
[21]. This algorithm identifies individuals with CKD using
combinations of diagnoses codes, drug prescriptions and
procedures found in the SNDS. Because the SNDS does
not contain lab values, we could not distinguish individu-
als based on their CKD stage. This yielded two cohorts of
individuals with CKD who were followed for two years. The
2019 cohort included individuals exposed to the COVID 19
pandemic (follow-up from January 1, 2020 to December 31,
2021). The 2017 cohort was considered the control popula-
tion and included individuals unexposed to the pandemic
(follow-up from January 1, 2018 to December 31, 2019).
Patients who initiated KRT (dialysis or kidney transplant) or
who died during the year of identification (from January 1 to
December 31, 2017 for the 2017 cohort and from January 1
to December 31, 2019 for the 2019 cohort) were excluded.

## Data collection

From the SNDS, the following data were collected at base-
line (i.e., 2017 or 2019): age, sex, region of residence and
city-level deprivation index (in quintiles: Q5 is the most
disadvantaged [22]). Additionally, data on comorbidities
were collected including diabetes, cancer, cardiovascular
diseases, psychiatric diseases, neurological or degenera-
tive diseases, chronic respiratory diseases, inflammatory
or rare diseases, HIV or AIDS, vascular risk management
(without pathology), and psychotropic treatments (without
pathology). The complete French social security method-
ology for comorbidity identification is available at https://
www.assurance-maladie.ameli.fr/sites/default/files/2024_

methode-reperage-pathologiesCartographie.pdf. During the
2 years of follow-up of each cohort, all outpatient visits car-
ried out by a general practitioner (GP) or nephrologist were
extracted from the SNDS. Consultations were divided into
teleconsultations and in-person consultations using the spe-
cific French Nomenclature of Care Reimbursement (Nature
des prestations: 1191, 1192, 1157, 1164, 1096, 1097, 1193,
1194, 1158, 1165, 1172, 1174). All hospitalizations were
also extracted and divided into day hospital care (< 24 h
of stay, all diagnoses) and hospitalizations for > 24 h (all
diagnoses). Hospitalizations with COVID-19 as the main or
related diagnosis (ICD-10 codes: U07.10 COVID-19, respir-
atory form, virus identified; U07.11 COVID-19, respiratory
form, virus unidentified; U07.14 COVID-19, other clinical
forms, virus identified; and U07.15 COVID-19, other clini-
cal forms, virus unidentified) were excluded.

## Statistical analysis

We assessed the comparability of the two cohorts. Their char-
acteristics were reported using frequencies and percentages
for categorical variables and median and interquartile range
for continuous variables. The two years of follow-up after
the year of identification (N) were divided into eight periods
according to the lockdown periods in France during the pan-
demic: period 1 (pre-pandemic, 01/01/N + 1–16/03/N + 1),
period 2 (first lockdown, 17/03/N + 1–10/05/N + 1), period
3 (post-first lockdown, 11/05/N + 1–29/10/N + 1), period
4 (second lockdown, 30/10/N + 1–14/12/N + 1), period 5
(post-second lockdown, 15/12N + 1–02/04/N + 2), period 6
(third lockdown, 03/04/N + 2–02/05/N + 2), period 7 (post-
third lockdown, 03/05/N + 2–09/06/N + 2) and period 8
(post-pandemic, 10/06/N + 2–31/12/N + 2) (Supplementary
Figure S1).

Mortality rates and cumulative death incidence were
compared between cohorts, stratified by age groups (< 60,
60–74 and ≥ 75 years of age). The percentage of patients
who had at least one healthcare service utilization in each
period (first and second year of follow-up) was calculated.
For each period, the sum of person-time alive was calcu-
lated and used as the denominator in order to neutralize the
effect of death. These percentages were compared in the
two cohorts for all periods and annually and for the total
population, stratified by age (same groups as above), and
between sexes (men and women). Because we included a
nationwide population and because the two cohorts were
not mutually exclusive, we chose to not perform statistical
tests of difference and report p-values. The cumulative inci-
dence of individuals receiving the first consultation during
the follow-up was calculated and plotted for both cohorts
to assess the trend of outpatient care use (GP and neph-
rologist). Additional exploratory analyses were carried out
by stratifying the sample according to age groups and sex, region of residence and city-level deprivation index.

# Results

## Description of the study population

Using the RENALGO algorithm, 4,866,096 individuals with CKD were identified in 2017 and 5,089,706 in 2019 (total n=1,890,460 patients) (Supplementary Figure S2). The two cohorts had similar characteristics and comorbidity profiles. The mean age was 62 years (standard deviation = 20.6) in the 2017 cohort and 63 years (standard deviation = 20.4) in the 2019 cohort. In both cohorts, women represented 59% of patients and 25% of patients had diabetes (Supplementary Table S1).

## Comparison of mortality rates

At the end of the 2 years of follow-up, 9.1% and 9.7% of patients had died in the 2017 cohort and in the 2019 cohort, respectively. The mortality rate was higher in the 2019 cohort than 2017 cohort during periods 2, 4 and 6 (i.e. the lockdown periods) (Supplementary Figure S3). In the 2019 cohort, the COVID-19 mortality rate was higher during the lockdown periods (19.8% and 21.2% during the first and the second lockdown) than during the post-pandemic period (4.0%).

## Comparison of outpatient healthcare utilization

In the 2019 cohort, 94% of the 5,089,706 patients had at least one consultation (in-person or teleconsultation) with a GP during the first year of follow-up (N+1). This was slightly lower (–1.3%) than in the 2017 cohort (95.2%) (Table 1). The percentage was similar between cohorts during the second year of follow-up (N + 2). The greatest decreases in the 2019 cohort were observed during period 2: –12.9% when considering all consultations with a GP (60.3% of patients in the 2017 cohort had at least one consultation vs 52.7% in the 2019 cohort) and -32.8% when considering only in-person consultations. Comparison of the cumulative incidence of the first consultation with a GP during the follow-up period showed that despite an apparent reduction during period 2 (first lockdown), the percentage of patients in cohort 2019 with at least one consultation steadily increased over the 2 years of follow-up (Fig. 1).

Overall, there was no difference in the proportion of patients who had at least one consultation (in-person or teleconsultation) with a nephrologist during the first year of follow-up (6.4% in the 2017 cohort vs 6.3% in the 2019 cohort). Regarding GP consultations, in the 2019 cohort, the

proportion of patients who had at least one consultation with a nephrologist was lower during period 2, even when considering both teleconsultations and in-person consultations (0.8% vs 1.6% in the 2017 cohort, 50% decrease). Comparison of the cumulative incidence of the first consultation with a nephrologist during the follow-up period again showed a reduction in period 2 followed by a progressive increase over time (Fig. 2). When only in-person consultations were considered, the proportion of patients with at least one consultation with a nephrologist strongly decreased in the 2019 cohort during periods 2, 4 and 6 (i.e., first, second and third lockdown) by 75%, 12.5% and 11.1% compared with the 2017 cohort.

## Comparison of inpatient healthcare utilization

Table 2 presents the percentages of patients with at least one <24 h hospitalization or one ≥ 24 h hospitalization during the follow-up. The percentage of patients with at least one <24 h hospitalization slightly decreased in the 2019 cohort during the first year of follow-up (27.3% in the 2017 cohort vs 26% in the 2019 cohort). The most significant decrease (-36.5%) was observed during period 2. However, during the second year of follow-up, slightly more patients in the 2019 cohort had at least one <24 h hospitalization (25% in 2017 cohort vs 26.2% in the 2019 cohort).

The percentage of patients with at least one ≥ 24 h hospitalization was lower in the 2019 cohort during the first year of follow-up (27% in the 2017 cohort vs 24.1% in the 2019 cohort) and also in the second year of follow-up and throughout all periods. The most important reductions in the 2019 cohort were observed during the lockdown periods (31.7%, -23.3% and -18.5% for periods 2, 4 and 6, respectively).

## Stratification analyses

The additional analyses did not show any difference in outpatient consultation rates between cohorts when stratified according to sex (Supplementary Figure S4), age groups (Supplementary Figure S5), and by sex and age groups (Supplementary Table S2). Similar results were obtained when patients were stratified based on the city-level deprivation index (Supplementary Table S3), despite the higher consultation rates in socioeconomically advantaged areas and higher proportions of hospital use in the most deprived areas. The cumulative incidence of GP and nephrologist consultations followed different dynamics between regions (Supplementary Figures S6, S7). However, there was no difference in the proportion of patients with a consultation at the end of the 2 years of follow-up between the 2017 and 2019 cohort.
<table><caption>**Table 1** Percentages of patients in each cohort who consulted a GP at least once and a nephrologist at least once in each period in person-time, adjusted for deaths</caption><thead><tr><th rowspan="3"></th><th colspan="6">All consultations (in-person consultations and teleconsultations<sup>a</sup>)</th><th colspan="6">Only in-person consultations</th></tr><tr><th colspan="3">% of patients with ≥ 1 GP consultation</th><th colspan="3">% of patients with ≥ 1 nephrologist consultation</th><th colspan="3">% of patients with ≥ 1 GP consultation</th><th colspan="3">% of patients with ≥ 1 nephrologist consultation</th></tr><tr><th>2017 cohort</th><th>2019 cohort</th><th>Relative difference<sup>b</sup></th><th>2017 cohort</th><th>2019 cohort</th><th>Relative difference<sup>b</sup></th><th>2017 cohort</th><th>2019 cohort</th><th>Relative difference<sup>b</sup></th><th>2017 cohort</th><th>2019 cohort</th><th>Relative difference<sup>b</sup></th></tr></thead><tbody><tr><td>Year N+1</td><td>95.2</td><td>94.0</td><td>-1.3</td><td>6.4</td><td>6.3</td><td>-1.6</td><td>95.2</td><td>94.0</td><td>-1.3</td><td>6.4</td><td>6.3</td><td>-1.6</td></tr><tr><td>Year N+2</td><td>92.5</td><td>92.4</td><td>-0.1</td><td>6.1</td><td>6.5</td><td>6.6</td><td>92.4</td><td>92.4</td><td>0</td><td>6.1</td><td>6.4</td><td>4.9</td></tr><tr><td>Period 1</td><td>73.9</td><td>72.4</td><td>-2.2</td><td>2.4</td><td>2.5</td><td>4.2</td><td>73.9</td><td>72.3</td><td>-2.2</td><td>2.4</td><td>2.4</td><td>0</td></tr><tr><td>Period 2</td><td>60.3</td><td>52.5</td><td>-12.9</td><td>1.6</td><td>0.8</td><td>-5.0</td><td>60.3</td><td>40.5</td><td>-32.8</td><td>1.6</td><td>0.4</td><td>-75</td></tr><tr><td>Period 3</td><td>86.4</td><td>93.5</td><td>8.2</td><td>4.2</td><td>4.3</td><td>2.4</td><td>86.4</td><td>84.3</td><td>-2.4</td><td>4.2</td><td>4.0</td><td>-4.8</td></tr><tr><td>Period 4</td><td>56.8</td><td>55.6</td><td>-2.1</td><td>1.7</td><td>1.5</td><td>-11.8</td><td>56.8</td><td>51.2</td><td>-9.9</td><td>1.6</td><td>1.4</td><td>-12.5</td></tr><tr><td>Period 5</td><td>79.1</td><td>83.9</td><td>6.1</td><td>2.9</td><td>3.1</td><td>6.9</td><td>79.0</td><td>76.5</td><td>-3.2</td><td>2.9</td><td>2.9</td><td>0</td></tr><tr><td>Period 6</td><td>38.9</td><td>38.7</td><td>-0.5</td><td>0.9</td><td>0.9</td><td>0</td><td>38.9</td><td>36.6</td><td>-5.9</td><td>0.9</td><td>0.8</td><td>-11.1</td></tr><tr><td>Period 7</td><td>46.7</td><td>47.3</td><td>1.3</td><td>1.3</td><td>1.3</td><td>0</td><td>46.7</td><td>45.2</td><td>-3.2</td><td>1.2</td><td>1.3</td><td>8.3</td></tr><tr><td>Period 8</td><td>85.2</td><td>90.7</td><td>6.5</td><td>4.5</td><td>4.7</td><td>4.4</td><td>85.1</td><td>85.2</td><td>0.1</td><td>4.5</td><td>4.7</td><td>4.4</td></tr></tbody></table>

<footnote><sup>a</sup>No teleconsultation was found in 2018 because it was only introduced as a procedure in France in late 2018</footnote>

<footnote><sup>b</sup>(2017 proportion – 2019 proportion)/2017 proportion</footnote>
<figure><img src="image_12.png" /><figcaption>**Fig. 2** Cumulative incidence of a first nephrologist consultation in the 2017 and 2019 cohorts during the follow-up</figcaption></figure>

<figure><img src="image_13.png" /></figure>

Discussion

In this nationwide population-based study, we assessed
the impact of the COVID-19 pandemic on healthcare use
by patients with CKD in France. The mortality rate was
higher in the 2019 cohort during the lockdown periods

than in the 2017 cohort in the equivalent periods. Indeed,
the COVID-19 mortality rates were higher during the
lockdown periods and declined slowly after the third
lockdown. The level of outpatient healthcare use remained
stable, with minimal changes in consultation rates with
GPs and nephrologists. Thanks to teleconsultations, the
proportion of patients who had at least one consultation

<figure><img src="image_14.png" /></figure>
<table><caption>**Table 2** Percentage of patients in each cohort with at least one hospital stay in each period, in person-time, adjusted for deaths</caption><thead><tr><th rowspan="2"></th><th rowspan="2"></th><th colspan="3">% of patients with ≥ 1 hospital stay for < 24 h</th><th colspan="3">% of patients with ≥ 1 hospital stay > 24 h</th></tr><tr><th>2017 cohort</th><th>2019 cohort</th><th>Relative difference</th><th>2017 cohort</th><th>2019 cohort</th><th>Relative difference</th></tr></thead><tbody><tr><td>Year N + 1</td><td></td><td>27.3</td><td>26</td><td>-4.8</td><td>27.0</td><td>24.1</td><td>-10.7</td></tr><tr><td>Year N + 2</td><td></td><td>25.0</td><td>26.2</td><td>4.8</td><td>21.2</td><td>19.1</td><td>-9.9</td></tr><tr><td>Period 1</td><td>01/01/N + 1-16/03/N + 1</td><td>10.4</td><td>11.1</td><td>6.7</td><td>10.1</td><td>9.7</td><td>-4.0</td></tr><tr><td>Period 2</td><td>17/03/N + 1-10/05/N + 1</td><td>7.4</td><td>4.7</td><td>-36.5</td><td>6.3</td><td>4.3</td><td>-31.7</td></tr><tr><td>Period 3</td><td>11/05/N + 1-29/10/N + 1</td><td>15.1</td><td>15.5</td><td>2.6</td><td>12.8</td><td>11.7</td><td>-8.6</td></tr><tr><td>Period 4</td><td>30/10/N + 1-14/12/N + 1</td><td>6.3</td><td>6.2</td><td>-1.6</td><td>4.3</td><td>3.3</td><td>-23.3</td></tr><tr><td>Period 5</td><td>15/12/N + 1-02/04/N + 2</td><td>10.8</td><td>11.4</td><td>5.6</td><td>8.8</td><td>7.3</td><td>-17.0</td></tr><tr><td>Period 6</td><td>03/04/N + 2-02/05/N + 2</td><td>4.3</td><td>4.4</td><td>2.3</td><td>2.7</td><td>2.2</td><td>-18.5</td></tr><tr><td>Period 7</td><td>03/05/N + 2-09/06/N + 2</td><td>5.1</td><td>5.6</td><td>9.8</td><td>3.3</td><td>3.0</td><td>-9.1</td></tr><tr><td>Period 8</td><td>10/06/N + 2-31/12/N + 2</td><td>15.8</td><td>17.0</td><td>7.6</td><td>12.9</td><td>11.9</td><td>-7.8</td></tr></tbody></table>

did not change much between cohorts. The consistency of these results across age groups, sex and socioeconomic indicators provides reassurance that outpatient healthcare continuity was largely maintained despite the pandemic. Nonetheless, the persistent decline in inpatient healthcare use raises concerns about possible implications for long-term health outcomes in individuals with CKD.

Our findings are consistent with previous French reports. Tuppin et al. found only a -3% decrease of the proportion of the total French population with at least one consultation with a GP in 2020 compared with 2019 [6]. In addition, our study showed that this proportion remained stable for individuals with CKD exposed to the COVID-19 pandemic, both in 2020 and 2021, despite a greater decrease at specific time points during the pandemic (i.e. the three lockdown periods). It also found that the proportions of individuals with CKD having a consultation with a nephrologist remained the same at the yearly level.

One important finding of our study is that teleconsultations allowed compensating the deficit of in-person consultations with GPs and nephrologists throughout the lockdown periods in 2020 and 2021. A study in the US reported a decrease of outpatient consultations for individuals with CKD (N=250,000) that was not sufficiently compensated by teleconsultations in 2020 and 2021 [23]. This difference can be attributed to variations in healthcare coverage as well as methodological considerations, since healthcare use was calculated differently (mean number of consultations per individual in the US study vs percentage of individuals with at least one consultation in our study). It is worth noting that in France, the definition of a teleconsultation for reimbursement eligibility was extended at the time of the first lockdown from video consultation to telephone call. This could have influenced the frequencies, thus making international comparisons difficult. Nevertheless, teleconsultations (by telephone or videoconference) have shown their benefits

for patient and healthcare continuity in primary practice and nephrology settings [24, 25]. It seems to truly have replaced in-patient consultations during the lockdowns because there was no increase in consultations after the lockdown. Indeed, teleconsultation was probably a good option for well-known patients with chronic diseases, but more difficult for patients with acute medical problems, as reported by Tuppin et al. [20].

Hospitalization for ≥ 24 h of individuals with CKD persistently decreased in the 2019 cohort during the two years of followup, and particularly during the lockdown periods. Several explanations can be hypothesized. First, the 2021 inpatient activity in France was still lower than the 2019 pre-pandemic activity [26], with cancellation and postponement of hospitalizations. Mounting evidence suggests that this could be of concern for long-term health outcomes [7–9, 27]. Moreover, lockdowns and related restrictions might have reduced the environmental triggers to hospitalizations. Similarly, Mesnier et al. observed in France a decrease in hospital admissions for acute myocardial infarctions following the first lockdown [28]. Therefore, the reasons for hospital admissions should be better explored to understand the persistent decrease.

By focusing on the population of individuals with CKD not treated by KRT, our study completes previous reports on the impact of the COVID-19 pandemic on dialysis initiation and kidney transplantation. The Renal Epidemiology and Information Network (REIN) registry has prospectively collected new cases of KRT in France since 2002 [29]. Based on their numbers, the incidence of individuals treated by KRT decreased between 2019 and 2022 (175.6 per million inhabitants in 2019, 164.7 in 2020, 168.6 in 2021 and 163 in 2022). One explanation for this decrease is the death of individuals with advanced stages of CKD who died due to COVID-19 before reaching the need for KRT (https://www.agence-biomedecine.fr/Les-chiffres-du-R-E-I-N). Similar
data were reported in the US [30]. Additionally, disruptions
in care could have negatively impacted the progression to
kidney failure, particularly for patients with advanced stages
of CKD. Indeed, those patients require a close follow-up in
nephrology and potential preparation to KRT. The REIN
registry prospectively records whether dialysis treatment is
initiated in emergency or not, and the REIN numbers indi-
cate a sustained slight increase of emergency initiations (in
2019: 25% of hemodialysis initiations, 2020: 26%, 2021:
29%, 2022: 30%) [31, 32]. In the initial phase of the pan-
demic in 2020, premature deaths of individuals with CKD
due to COVID-19 might explain why the proportion of
emergency initiations did not change. The sustained increase
in later years could indicate a residual, delayed effect of
changes in care delivery (i.e. less preparation to dialysis),
which strengthen the future importance of studying the
quality of care. Kidney transplantation activity was paused
for two months before progressively resuming in 2021 and
beyond. By 2024, the number of kidney transplants returned
to 2019 levels (3757).

In early 2020, France introduced a new capitation pay-
ment model [33]. Providers that opt-in receive an annual
payment per patient enrolled (CKD stage 4 and stage 5 non-
treated by dialysis). This new policy could be a confounder
to our analysis. First, receiving the payment relies on collect-
ing the number of visits with a nephrologist per patient and
sending it to an alternative information system, i.e. not trans-
ferred to the SNDS database, which we used in this study.
Thus, we could expect to observe a decrease in the visit rate
with nephrologists starting in 2020. However, preliminary
analysis on the capitation payment model data shows that
visits were still reported in the SNDS database. Conversely,
the new model could incentivize a more regular follow-up
and increase the observed visit rate. Assessing the effect of
the new model is difficult due to the fact that a) no link is
available between the data reported by the facilities and the
SNDS database, which means that we cannot investigate the
continuity of nephrology care at the individual level and b)
the model was not adopted by all providers at the same time.

The main limitation of this study is the inability to deter-
mine the CKD stage of the study population, as the SNDS does
not contain laboratory test results. This is important because
healthcare utilization varies across CKD stages [34, 35] and
the impact of COVID-19 likely varied as well [17]. The second
limitation is selection bias inherent to the RENALGO algo-
rithm, that relies on healthcare consumption data. Indeed, the
sensitivity of the algorithm is poor for individuals who do not
seek care or have not been diagnosed or whose care is inap-
propriate, which could ultimately underestimate the true extent
of the pandemic-related disruptions.

Our study has several strengths. The data used come from
an exhaustive source of in- and out-patient healthcare use
for nearly the whole French population. The SNDS database

also contains information on deaths, ascertained by cer-
tificate. This allowed calculating the mortality rates in the
2017 and 2019 cohorts in order to isolate the direct effect of
COVID-19 as a disruptive event for the healthcare system.

By comparing the 2017 and 2019 cohorts, it was assumed
that the COVID-19 pandemic was the only major contextual
difference and the reason for the observed differences. How-
ever, this design cannot exclude the effect of other changes.
For example, in 2020, France introduced a new capitation
payment model to improve the care of individuals with stage
4 and 5 CKD. This could have affected how consultations
with a nephrologist are provided and captured.

Our study focused on the quantitative aspect of healthcare
utilization. The quality of care should also be investigated. This
includes the effectiveness of teleconsultations in the context of
CKD for which robust data are still lacking [36, 37].

Conclusions

This study shows a reassuring continuity of outpatient care
for individuals with CKD in France during the 2 years fol-
lowing the COVID-19 pandemic, notably thanks to telecon-
sultations. The persistent decrease in inpatient healthcare use
warrants additional investigations.

**Supplementary Information** The online version contains supplementary material available at https://doi.org/10.1007/s40620-025-02376-5.

**Acknowledgements** The authors would like to thank all people involved in the REDSIAM (Réseau pour mieux utiliser les Données du Système national des données de santé) group who developed the RENALGO algorithm.

**Author contributions** MR and SB are the project administrators and conceived the study design. MR and JP prepared the data. JP carried out the analyses and wrote the manuscript. MR acquired the funding, oversaw the analyses and reviewed/edited the manuscript. SB, CV, CC provided intellectual input, including clinical interpretation, and reviewed/edited the manuscript.

**Funding** Open access funding provided by Karolinska Institute. This study benefited from a grant from the French Biomedicine Agency (ABM), *appel d'offre du Registre REIN, #21REIN006*.

**Data availability** The dataset analyzed in this study is not publicly available due to French law which forbids sharing data from a SNDS data extraction.

Declarations

**Conflict of interest** On behalf of all the authors, the corresponding au-
thor states that there is no conflict of interest. The results presented in
this paper have not been published previously in whole or part, except
in abstract form.

<figure><img src="image_15.png" /></figure>
**Ethical approval** This retrospective study was performed in accordance with the ethical standards of the institutional and national research committee.

**Informed consent to participate** SNDS is a pseudonymized database and no individual patient consent was required.

**Open Access** This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

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