Measurement of physical function is important to guide physical therapy for patients post-lung transplantation (LTx). The Sit-to-Stand (STS) test has proven utility in chronic disease, but psychometric properties post-LTx are unknown. The study aimed to assess reliability, validity, responsiveness, and feasibility of the 60-second STS post-LTx.
This was a measurement study in 62 inpatients post-LTx (31 acute postoperative; 31 medical readmissions). Interrater reliability was assessed with 2 STS tests undertaken by different assessors at baseline. Known group validity was assessed by comparing STS repetitions in postoperative and medical groups. Content validity was assessed using comparisons to knee extensor and grip strength, measured with hand-held dynamometry. Criterion validity was assessed by comparison of STS repetitions and 6-minute walk distance postoperatively. Responsiveness was assessed using effect sizes over inpatient admission.
Median (interquartile range) age was 62 (56–67) years; time post-LTx was 5 (5–7) days postoperative and 696 (244–1849) days for medical readmissions. Interrater reliability was excellent (intraclass correlation coefficient type 2,1 = 0.96), with a mean learning effect of 2 repetitions. Repetitions were greater for medical at baseline (mean 18 vs 8). More STS repetitions were associated with greater knee extensor strength (postoperative r = 0.57; medical r = 0.47) and 6-minute walk distance (postoperative r = 0.68). Effect sizes were 0.94 and 0.09, with a floor effect of 23% and 3% at baseline (postoperative/medical) improving to 10% at discharge. Patients incapable of attempting a STS test were excluded, reducing generalizability to critical care. Physical rehabilitation was not standardized, possibly reducing responsiveness.
The 60-second STS demonstrated excellent interrater reliability and moderate validity and was responsive to change postoperatively.
The 60-second STS represents a safe, feasible functional performance tool for inpatients post-LTx. Two tests should be completed at each time point.