Table 1.

Measures used to operationalize the physical frailty indicators.

Physical frailty indicator	Instrument	Operationalization
Body Mass Index (BMI)	Self-report	BMI was calculated by dividing weight in kilograms by height in meters squared.
Gait speed	Timed Up and Go (TUG) test	The TUG test measures the time the respondent takes to rise from an armchair, walk three meters, and return to the chair.
Physical activity	LASA Physical Activity Questionnaire (LAPAQ), self-report	Participants were asked how often and how long in the 2 weeks before the interview they had walked, bicycled, and performed sport activities and light and heavy household activities. The total time spent on physical activity was calculated by multiplying the frequency by the duration of each activity, divided by 14.
Hand grip strength	Martin Vigorimeter	Hand grip strength of the dominant hand was measured three times. The highest value was used.
Fatigue	Shortened Fatigue Questionnaire (SFQ), self-report	The SFQ consists of four statements which the person answers by checking an item at a 7-point scale. In this study a 3-point scale was used (yes that is correct, that is more or less correct, and no that is not correct).
Balance	Four-test balance scale	The Four-test balance scale includes four timed static balance tasks of increasing difficulty that are completed without assistive devices. Respondents were asked to hold each position for 10 seconds. In this study participants performed three tasks: side-by-side, semitandem, and tandem. If respondents could not perform at least one of these three tasks, then balance was coded as poor.