Construct validity of self-reported and interview-guided administration methods of the Danish version of the [PCFS], 2025, Sørensen+

[SNT Gatchaman]

Construct validity of self-reported and interview-guided administration methods of the Danish version of the post-COVID−19 functional Status scale

Spoiler: Authors

Sørensen, Lotte; Agergaard, Jane; Nielsen, Trine Brøns; Schiøttz-Christensen, Berit; Laursen, Cecilia Hee; Leth, Steffen; Nielsen, Claus Vinther; Oestergaard, Lisa Gregersen

INTRODUCTION
The Post-COVID-19 Functional Status (PCFS) scale was quickly adopted into COVID-19 research and clinical practice worldwide to monitor functional status and recovery. The scale has been translated into Danish, and three different administration methods have been employed. However, clinicians have expressed concerns about the scales ability to capture work-related functional limitations. Therefore, the purpose of this study was to evaluate the construct validity of three different administration methods of the Danish version of the PCFS scale.

METHODS
This cross-sectional study included patients with long COVID who completed three versions of the PCFS scale: a questionnaire-based version, a flowchart-based version, and an interview-based version. The construct validity was evaluated following the Consensus-based Standards for the selection of health Measurement Instruments (COSMIN) guidelines by testing predefined hypotheses that compared the PCFS scale with sick leave and EuroQoL Five-dimensions Five level (EQ-5D-5l).

RESULTS
A total of 437 patients, with a mean age 48 years, 75% female, and 59% on sick leave, were included in this study. Statistically significant differences between the three administration methods were found. Of the 234 patients on sick leave, only 50%-54% had a PCFS grade ≥3 which was below our predefined hypothesis. Furthermore, correlations between the PCFS scale and EQ-5D-5l was lower than hypothesized.

CONCLUSION
None of the three administration methods effectively captured work-related functional limitations associated with being on part-time or full-time sick leave. Additionally, correlations with quality of life were lower than expected. Overall, the construct validity of the PCFS scale was only partially supported.

Web | DOI | PDF | Frontiers in Rehabilitation Sciences | Open Access

 

[Utsikt]

Primary hypothesis​

At least 80% of the patients reporting sick leave (part-time or full-time) had a PCFS score of 3 or higher.

Secondary hypotheses​

The correlation between the EQ-5D-5l total score and the PCFS scale was 0.30-0.50.

The correlation between the EQ-5D-5l domain “usual activities” and the PCFS scale was ≥ 0.50.

The correlation between the EQ-5D-5l domain “mobility” and the PCFS scale was 0.30-0.50.

The correlation between the EQ-5D-5l domain 'self-care' and the PCFS scale was 0.30-0.50.

The correlation between the EQ-5D-5l domain “pain/discomfort” and the PCFS scale was 0.30-0.50.

The correlation between the EQ-5D-5l domain “anxiety/depression” and the PCFS scale was <0.30.

The construct validity of the PCFS scale was considered acceptable if the primary hypothesis was accepted. The validity was further supported if ≥75% of the secondary hypotheses were accepted.

So they have outlines very clear thresholds that should be met.

Testing the primary hypothesis revealed that none of the versions of the PCFS scale demonstrated acceptable construct validity.

Of 234 patients reporting sick leave (part-time or full-time), 127, 54% (95% CI 48;61) had a PCFS grade of 3 or higher using the interview-based version, 125, 53% (95% CI 47;60) using the questionnaire-based version, and 116, 50% (95% CI 43;56) using the flowchart-based version.

A sensitivity analysis including all patients completing the interview-based version (n = 583) showed similar results; of the 309 patients reporting sick leave, 158, 51% (95% CI 45;57) had a PCFS grade of 3 or higher.

The primary hypothesis clearly failed.

Furthermore, the construct validity was not supported by the secondary hypotheses, as less than 75% were accepted (33% for the interview-based and the flowchart-based version and 50% for the questionnaire version) (Table 6).

The secondary hypothesis clearly failed.

CONCLUSION
None of the three administration methods effectively captured work-related functional limitations associated with being on part-time or full-time sick leave. Additionally, correlations with quality of life were lower than expected. Overall, the construct validity of the PCFS scale was only partially supported.

Yet somehow they manage to conclude that the construct validity was partially supported!

At least they demonstrated that the questionnaires are bad no matter how you use them. I just wish they were able to accept the logical conclusion that they should ditch them all..

 

[Sean]

Yes, the correct interpretation being they are all equally bad and useless, and worse in being potentially misleading.

 

[Eleanor]

Early in the pandemic, the Post-COVID-19 Functional Status (PCFS) scale was introduced (11) as a slightly adapted version of the Post-Venous thromboembolism Functional Status scale

Another example of the assumption early in the pandemic that the sequelae of Covid-19 would mainly involve respiratory complications. It's good that the failings of this approach are being recognised.

These findings highlight the need to revalidate existing tools for new clinical populations and to develop measures that more accurately reflect the functional impact of long COVID.

Return-to-work evaluations should not be based exclusively on PCFS grade, but instead incorporate a comprehensive appraisal of functional capacity and symptom persistence. Furthermore, revalidation of the underlying structure of the PCFS scale is recommended, including a thorough factor analysis to examine its dimensionality and ensure that the scale accurately reflects the intended construct of post-COVID functional status.

 

[Kitty]

Return-to-work evaluations should not be based exclusively on PCFS grade, but instead incorporate a comprehensive appraisal of functional capacity and symptom persistence.

Revolutionary thought for the day: you could ask them, the way a doctor would in a consultation.