Physical functioning

Functional limitations


LASA030
LASA230
LASA603
LASA703

Contact: Dorly Deeg

Background
In the disablement process, functional limitations form the link between impairment and disability [Verbruge & Jette, 1994]. Impairments are dysfunctions and significant structural abnormalities in specific body systems. Functional limitations are restrictions in performing fundamental physical and mental actions used in daily life such as mobility (physical) or memory (mental). Disability is difficulty experienced doing activities of daily living in any domain of life due to a health or physical problem. The measurement of functional limitations and activities of daily living can be based either on self-reports, or on observation of actual performance. For functional limitations, both are available in LASA. The following considerations may be helpful in deciding which to use when dealing with a specific research question.
Whereas performance tests assess actual physical functioning at a specific moment, questionnaires on functional limitations assess actual functioning averaged over a longer period of time and in different environments [Myers et al., 1993]. Accordingly, they come closer to covering true daily functioning than performance tests. Note, however, that questions on functional limitations assess potential or hypothetical ability because they are phrased not in terms of 'do' but in terms of 'can'. The responses to these questions may be more sensitive to personal factors (mood, perceived competence) than performance tests [Kempen et al., 1996]. Furthermore, because of their greater sensitivity in the higher ability range, timed performance tests are able to detect functional decline that is still imperceptible to respondents and thus not picked up by self-reports [Guralnik et al., 1989]. However, some authors consider performance tests as assessing hypothetical ability as well because of their experimental nature [Glass, 1998].

Measurement instruments in LASA
The selection of questions on functional limitations is based on pilot studies prior to the start of the first LASA cycle [Smits et al., 1997]. These questions were derived from nine items in the OECD questionnaire [McWhinnie 1981], which was translated into Dutch and validated by the Netherlands Central Bureau of Statistics [Van Sonsbeek, 1988]. The selected questions constituted a parsimonious set [Verbrugge 1999], based on a pilot study using iterative elimination of the item with the lowest item-rest correlation until three items were left [Smits et al. 1997]. Test-retest reliability is reported by Boshuizen et al [2000]. The selected activities are expected to be sensitive to changes over time, because they indicate mild levels of functional limitation. Three items proved to form the best scale:

Can you walk up and down a staircase of 15 steps without resting?
Can you use your own or public transportation?
Can you cut your own toenails?

Response categories used in LASA-B were:
0. Yes, without difficulty
1. Yes, with difficulty
2. Only with help
3. No, I cannot

The items can be summed to a scale in three ways:
1) Defining functional limitations: counting the number of items 'with difficulty' or worse (range 0-3, internal reliability 0.73)
2) Defining disability: counting the number of items 'with help' or worse (range 0-3, internal reliability 0.71)
3) Functional limitations scale: summing the items irrespective of the content of the response categories (range 0-9, internal reliability 0.77).

The first scale is considered to indicate functional limitations in terms of difficulty, the second to indicate disability in terms of help needed, and the third scale combines these two aspects with the advantage that the greater range enables better differentiation. It should be noted that the three items are selected to represent the larger concept of functional limitations, and should not be used as single items.

By the second LASA cycle (LASA-C), it was felt that three items might not be sufficient to catch aging-related declines in physical functioning. The three items were then supplemented with three items that were used in the NESTOR-LSN-study:

Can you dress and undress yourself?
Can you sit down and stand up from a chair?
Can you walk outside during five minutes without stopping?

The first two of these questions are generally considered as activities of daily living (ADL's), rather than functional limitations [Katz et al., 1963; Lawton & Brody, 1969]. However, the borderline between actions and activities is very thin [Kempen & Suurmeijer, 1990]. The three questions correspond to three tests of physical performance as included in LASA.
Since the response categories of the LSN-items numbered five rather than four, from the second LASA-cycle, all items were asked with five response categories to obtain optimal differentiation:
0. Yes, without difficulty
1. Yes, with some difficulty
2. Yes, with much difficulty
3. Only with help
4. No, I cannot

Again, the total of six items can be summed to a scale in three ways:

  1. Defining functional limitations: counting the number of items 'with some difficulty' or worse (for 6 items: range 0-6, internal reliability 0.85), or 'with much difficulty' or worse (range 0-6, internal reliability 0.84)
  2. Defining disability: counting the number of items 'with help' of worse (range 0-6, internal reliability 0.80)
  3. Functional limitations scale: summing the items irrespective of the content of the response categories (range 0-24, internal reliability 0.85).

In these scales, low scores indicate few limitations, and high scores, many limitations.
Note that option 1) counts items with ‘some difficulty’ from LASA-C onwards, which may not capture the same degree of limitations as just ‘difficulty’ at LASA-B. Thus, this option does not yield measures that are comparable across all LASA-cycles. This problem does not exist using option 2). To make the sum scores of option 3) comparable to LASA-B, one can use for LASA-B the sum score of six items based on the available items at LASA-B plus an imputation based on LSN-A (measured 10 months earlier) for the remaining items. Alternatively, the original three items can be used, but the five response categories now add up to 12 instead of 9. This can be aligned by multiplying the sum score by ¾ from LASA-C onwards.


Availability of information per wave1

WAVE LSNa B C t D E
2B*
F G H

3B*
MB* I*
Stairs ma 030 ma
030
230
ma
030
230
  ma
030
230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
      tel
603
tel

703
tel
603
703
tel
603
703
  tel
603
703
tel
603
703
tel
603
703
    tel
603
703
                           
Transport
ma
030
230
ma
030
230


ma
030
230

ma
030

230

ma
030
230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
      tel
603
tel

703
tel
603
703
tel
603
703
  tel
603
703
tel
603
703
tel
603
703
    tel
603
703
                           
Toenails ma
030
230
ma
030
230



ma
030
230
ma
030

230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
      tel
603
tel

703
tel
603
703
tel
603
703
  tel
603
703
tel
603
703
tel
603
703
    tel
603
703
                           
Dress ma 030
  ma
030
230
  ma
030
230
ma
030

230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
ma
030
ma
030
230
      tel
603
tel

703
tel
603
703
tel
603
703
  tel
603
703
tel
603
703
tel
603
703
    tel
603
703
                           
Chair ma 030   ma
030
230
  ma
030
230
ma
030

230
ma
030
230
ma
030
23
ma
030
230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
      tel
603
tel

703
tel
603
703
tel
603
703
  tel
603
703
tel
603
703
tel
603
703
    tel
603
703
                           
Walk ma 030   ma
030
230
  ma
030
230
ma
030

230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
      tel
603
tel

703
tel
603
703
tel
603
703
  tel
603
703
tel
603
703
tel
603
703
    tel
603
703
                           
Shower/ bathe      


    ma
030
230
ma
030
230
ma
030
230
ma
030
230
ma
030
230
   

1 More information is available on:
http://www.lasa-vu.nl/data/lasa/sampleLASAdatacollection.html

* 2B=baseline second cohort;
   3B=baseline third cohort (Under Construction)
   MB=migrants: baseline first cohort (Under Construction);
   I=Under Construction

ma: data collected in main interview (LSNa030 / LASA030 / LASA230 for sumscores)
tel: data collected in telephone interview (LASAC603 / LASAD603, LASAD703 / LASAE603 / LASAE703 / LASAF603 /LASAF703 / LASAG603 / LASAG703 / LASAH603 / LASAH703 / LASAI603 / LASAI703)

Starting with the baseline cycle In the LASA-cohort recruited in 2002, a seventh item was added to improve possibilities for international comparison (Pluijm et al., 2005:
- Can you take a shower or bathe?
This item again has five response categories (see LAS2B030).

Another 12 items on functional limitations are available focusing on back problems [Raspe et al., 1990; Kohlmann & Raspe, 1994]. These are included in the medical interview for the study of Falls and Fractures (LASAC183: CMVAR401 through CMVAR412).

Use of assistive devices or assistance (see LASA*030)

The use of assistive devices was determined by a branching question following each item, asking if the respondent used an assistive device for this activity (response options: 1. no, 2. yes). This is the recommended approach to assess the use of assistive devices (Agree et al., 2003).

The use of personal assistance was determined by a second branching question following each item (response options: 1. no, 2. yes). A further branching question asked about the frequency of this assistance: 1. never, 2. rarely, 3. sometimes, 4. often or always.

Both questions were not asked of respondents who reported not being able to do the activity at all.

Avoidance

The usual questions on functional limitations may not capture the early beginnings of the disablement process, sometimes termed ‘preclinical disability’  [Fried et al., 1996], because people compensate for their limitations by changing their activity pattern. Therefore, from LASA-C through LASA-G a branching question was added after each item to achieve greater sensitivity of the functional limitations questionnaire:

Do you do this activity less often than you would want or than is necessary?

Response categories: 1. no, 2. yes.

Again, this question was not asked of respondents who reported not being able to do the activity at all.

This question can also be interpreted as measuring avoidance of activities.

Questionnaires
LASAB030 / LASAC030 / LASAD030 /LASAE030 /LAS2B030 / LASAF030 / LASAG030 / LASAH030 (main interview: in Dutch)

LASAC603 / LASAD603 / LASAE603 / LASAF603 / LASAG603 / LASAH603 (telephone interview with PROXY, in Dutch)
LASAD703 / LASAE703 / LASAF703 / LASAG703 / LASAH703 (telephone interview with RESP, in Dutch)

in C also with respondent

Variable information
LASAB030 / LASAC030 / LASAD030 /LASAE030 /LAS2B030 / LASAF030 / LASAG030 / LASAH030 (pdf)
LASA*230 (constructed variables, pdf)

LASAC603 / LASAD603 / LASAE603 / LASAF603 / LASAG603 / LASAH603;
LASAD703 / LASAE703 / LASAF703 / LASAG703 / LASAH703
(pdf, in preparation)

Previous use in LASA
At the first LASA cycle, the association between functional limitations self-reports and performance tests was moderate (Spearman correlation: 0.48; partial correlation, with age partialed out: 0.42) [Deeg, 1994]. Specific conditions that predicted incidence of functional limitations (defined as a transition from no difficulty with any item to difficulty with one or more items) were diabetes, stroke, arthritis and depression. Analysis of reliable change in functional limitations (defined according to the Edwards-Nunnally criterion [Speer & Greenbaum, 1995]) showed greater declines in older persons with lower socio-economic status as compared to higher socio-economic status [Broese van Groenou & Deeg 2000]. Combinations of somatic diseases had differential effects on functional decline [Kriegsman et al. 2004].

A review of all LASA-based research on functional limitations and disability can be found in Deeg et al. [2009 and 2012].

References

  1. Agree EM, Freedman VA. A comparison of assistive technology and personal care in alleviating disability and unmet need. The Gerontologist 43; 2003: 335-344.
  2. Boshuizen HC, Chorus A, Deeg DJH. Test-hertest betrouwbaarheid van de OECD-vragenlijst voor lichamelijke beperkingen [Test-retest reliability of the OECD-questionnaire on func­tional limitations]. Tijdschrift voor Gezondheidswetenschappen 78; 2000: 172-179. In Dutch.
  3. Broese van Groenou MI, Deeg DJH. Sociaal-economische dimensies van veranderingen in gezondheid bij ouderen [Socio-economic dimensions of changes in health of older adults]. Tijdschrift voor Gezondheidswetenschappen 78; 2000: 294-302. In Dutch.
  4. Deeg DJH. Performance tests of physical ability. In: Deeg DJH, Westendorp - de Serière M (eds). Autonomy and well-being in the aging population I: Report from the Longitudinal Aging Study Amsterdam 1992-1993. Amsterdam: VU University Press, 1994, pp. 21-29.
  5. Deeg DJH, Comijs HC, Thomése GC, Visser M. De Longitudinal Aging Study Amsterdam: een overzicht van 17 jaar onderzoek naar verandering in dagelijks functioneren [The Longitudinal Ageing Study Amsterdam: a survey of 17 years of research into changes in daily functioning] Tijdschrift voor Gerontologie en Geriatrie 40(6); 2009: 217-227.
  6. Deeg DJH, Kriegsman DMW. Measures of physical ability: which is best for monitoring change? In: Deeg DJH, Beekman ATF, Kriegsman DMW, Westendorp-de Serière M (eds). Autonomy and well-being in the aging population II: Report from the Longitudinal Aging Study Amsterdam 1992-1996. Amsterdam: VU University Press, 1998, pp. 43-54.
  7. Deeg DJH, Huisman M, Terwee CB, Comijs HC, Thomese GCF, Visser M. Changes in functional ability with ageing and over time. In: Phellas C (ed). Aging in European societies. Healthy aging in Europe. Series: International perspectives on aging 6. New York etc: Springer, 2012: 117-132.
  8. Fried LP, Bandeen-Roche K, Williamson JD, Prasada-Rao P, Chee E, Tepper S, Rubin GS. Functional decline in older adults: expanding methods of ascertainment. Journal of Gerontology: Medical Sciences 51A; 1996: M206-214.
  9. Glass TA. Conjugating the "tenses" of function: discordance among hypothetical, experimental, and enacted function in older adults. The Gerontologist 38; 1998: 101-112.
  10. Guralnik JM, Branch LG, Cummings SR, Curb JD. Physical performance measures in aging research. Journals of Gerontology 44(5); 1989: M141-146.
  11. McWhinnie JR. Disability assessment in population surveys: Results of the OECD common development effort. Revue Epidëmiologique et Santé Publique 29; 1981: 413-419.
  12. Katz S, Ford AB, Moskowitz RW, Jackson BA, Jaffe MW. Studies of illness in the aged. The index of ADL: A standardized measure of biological and psychosocial functioning. Journal of the American Medical Association 185; 1963: 914-919.
  13. Kempen GIJM, Steverink N, Ormel J, Deeg DJH. The assessment of ADL among frail elderly in an interview survey: Self-report versus performance-based tests and determinants of discrepancies. Journals of Gerontology: Psychological Sciences 51B; 1996: P254-P260.
  14. Kempen GI, Suurmeijer TP. The development of a hierarchical polychotomous ADL-IADL scale for noninstitutionalized elders. The Gerontologist 30(4); 1990: 497-502.
  15. Kohlmann T, Raspe HH. Die patientennahe Diagnostik von Funktionseinschrankungen im Alltag. Psychomed 6; 1994: 21-27.
  16. Kriegsman DMW, Deeg DJH, Stalman WAB. Comorbidity of somatic chronic diseases and decline in physical functioning. The Longitudinal Aging Study Amsterdam. Journal of Clinical Epidemiology 57; 2004: 55-65.
  17. Lawton MP, Brody EM. Assessment of older people: self-maintaining and instrumental activities of daily living. The Gerontologist 9; 1969; 179-186.
  18. Myers AM, Holliday PJ, Harvey KA, Hutchinson KS. Functional performance measures: are they superior to self-assessments? Journal of Gerontology: Medical Sciences 48; 1993: M196-M206.
  19. Pluijm SMF, Bardage C, Nikula S, Blumstein T, Jylhä M, Minicuci N, Zunzunegui MV, Pedersen NL, Deeg DJH, for the CLESA Study Working Group. A harmonized measure of activities of daily living was a reliable and valid instrument for comparing disability in older people across countries. Journal of Clinical Epidemiology 58; 2005: 1015-1023.
  20. Raspe HH, Hagesorn U, Hohlmann T, Matussek S. Der Funktionsfragebogen Hannover (FFbH): Ein Instrument zur Funktionsdiagnostik bei polyartikularen Gelenkerkrankungen. In: Siegrist J (ed). Wohnortnahe Betreuung Rheumakranker. Schattauer Verlag, Stuttgart 1990.
  21. Speer DC, Greenbaum PE. Five methods for computing significant individual client change and improvement rates: support for an individual growth curve approach. Journal of Consulting and Clinical Psychology 63; 1995: 1044-1048.
  22. Smits CHM, Deeg DJH, Jonker C. Cognitive and emotional predictors of disablement in older adults. Journal of Aging and Health 9; 1997: 204-21.11.
  23. Van Sonsbeek JLA. Methodological and substantial aspects of the OECD indicator of chronic functional limitations. Maandbericht Gezondheid (CBS) 1988, 88/6: 4-17.
  24. Verbrugge LM, Jette AM. The disablement process. Social Science and Medicine 38; 1994: 1-14.
  25. Verbrugge LM, Merrill SS, Liu X. Measuring disability with parsimony. Disability and Rehabilitation 1999, 21: 295-306.