The Effect of COVID‐19 Pandemic Restrictions on Laboratory Monitoring of Lithium Treated Outpatients in the Netherlands: A Controlled Interrupted Time Series Analysis

TL;DR

The study found that reduced lab monitoring during the early weeks of the COVID-19 lockdown in the Netherlands did not lead to significant health risks for lithium-treated patients.

Contribution

This is the first study to use a controlled interrupted time series analysis to assess the impact of pandemic restrictions on lithium monitoring in outpatients.

Findings

Monitoring for lithium, TSH, and renal function dropped significantly in the first week of lockdown.

No increase in abnormal serum levels or adverse outcomes was observed despite reduced monitoring.

The decline in monitoring gradually recovered during the lockdown period.

Abstract

The COVID‐19 pandemic restricted healthcare access. Mental illness in combination with isolation and fear of the virus possibly decreased routine monitoring for lithium using patients during the lockdown. Our aim was to study if monitoring frequencies and serum level values for lithium, TSH (thyroid stimulating hormone), and renal function changed during the COVID‐19 pandemic.

Using the PHARMO database (laboratory, pharmacy, and hospitalization data), we identified lithium users in The Netherlands over 2 years (14 October 2018–14 October 2020). The first year served as the control period; the second year was divided into pre‐COVID, lockdown, and post‐lockdown segments. A time series analysis with a linear regression model was performed to test for differences in monitoring frequency and aberrant serum levels at the beginning of the lockdown (immediate effect) and during the lockdown (post‐lockdown trend, effect over 12 weeks).

We identified 2835 patients using lithium. Monitoring measurements declined by 52% (7.74% vs. 4.01%) for lithium serum levels, 28% (5.56% vs. 4.20%) for TSH, and 26% (17.7% vs. 13.2%) for renal function in the first week of lockdown. These reductions were statistically significant compared to the control period. Monitoring for all measurements gradually recovered during lockdown. Changes in aberrant serum levels were not statistically different during the exposure and control periods.

Monitoring for lithium, TSH and renal function declined at the beginning of lockdown. However, it is unlikely that postponed laboratory measurements had clinically relevant negative treatment effects since no differences in aberrant serum levels were identified.

Monitoring measurements for lithium patients declined strongly in the first week of the COVID‐19 lockdown.The number of measurements declined with 52% for lithium serum levels, 28% for TSH, and 26% for renal function.No increase in sub‐ and supratherapeutic lithium serum levels, out of normal range TSH or eGFR below 60 mL/min was observed.Consequenses of reduced access to monitoring were limited on a population based‐level during the lockdown period.Guidance by (mental) health care professionals is important during periods of limited access to healthcare.

Monitoring measurements for lithium patients declined strongly in the first week of the COVID‐19 lockdown.

The number of measurements declined with 52% for lithium serum levels, 28% for TSH, and 26% for renal function.

No increase in sub‐ and supratherapeutic lithium serum levels, out of normal range TSH or eGFR below 60 mL/min was observed.

Consequenses of reduced access to monitoring were limited on a population based‐level during the lockdown period.

Guidance by (mental) health care professionals is important during periods of limited access to healthcare.

Lithium is a psychotropic drug which is used in a wide range of psychiatric conditions. Additional monitoring measurements for drug serum levels, thyroid function and renal function are required for patients who use lithium to ensure effectiveness and prevent side effects or toxicity. During the COVID‐19 lockdown period, access to healthcare was restricted. This research showed that monitoring measurements during the lockdown period declined. Despite a decline in measurements, there was no increase in measurements that were out of normal range during and after the lockdown period. Therefore, the consequences of reduced access to laboratory monitoring during a relatively short time period had limited impact on a population‐based level.

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