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Table 2 Included Cohort Studies

From: Multimorbidity and functional decline in community-dwelling adults: a systematic review

Author

Publication

Year

Country

Population and setting

Definition and prevalence of multimorbidity (MM)

Functional decline outcome measure/s

Follow-up period

Losses to follow-up (%)

Results

Abizanda

2014

Spain

General population

(FRADEA Study)

842 adults aged >70 yrs

MM ≥2 chronic diseases in a specific period of time.

14 pre-specified conditions selected for prevalence and impact on disability/mortality

Chronic diseases identified from medical records and coded via ICD-10

580 ≥ 2 conditions (69.0 %)

Barthel index (disability)

Fried’s criteria

(frailty)

2 years

7.5 % loss to follow-up

Disability and frailty was not associated with MM over two years.

Aarts

2012 Netherlands

Primary care

(Maastricht Aging Study)

1184 adults aged 21–84 years

MM ≥2 chronic diseases co-occurring within one person

Morbidities sourced from GP database including all current and past health problems by clinician

96 included conditions based on medical literature and clinical experience

35.5 % ≥ 2 chronic diseases

SF-36

3 and 6 years

16.4 % loss to follow-up

MM significantly associated with poorer physical functioning at all 3 follow-up points (p < 0.001)

Significant steep decline in physical function between 3 and 6 year follow up in those with MM (p < 0.001)

Participants whose morbidity status changed from baseline to 3 year follow up (either to single or MM) associated with significantly lower physical function (p < 0.001)

Bayliss

2004 USA

Primary care

(Medical Outcomes Study)

2708 adults, mean age 57.6 years

No definition of MM reported

Self-report of 7 pre-specified chronic conditions. Condition presence also sourced from records

Conditions chosen as of high prevalence in practice and in literature

686 ≥ 2 chronic diseases (25.3 %)

SF-36

(PCS scores)

4 years

41.9 % loss to follow up

≥4 chronic diseases associated with significant decline in physical function (p < 0.05)

Reduction in PCS by 6.5 used as criteria for clinically significant

<4 chronic diseases no association with physical decline

Congestive Heart Failure, diabetes and/or respiratory disease predictive of clinically significant decline in PCS (p <0.05)

Byles

2005 Australia

Primary care

(Veteran’s Affairs Preventative Care Trial)

1417 adults

≥70 years

Co-existence of multiple diseases in the same individual

Self-reported MM questionnaire consisting of 25 conditions

Severity measure incorporated and included mild cognitive decline

1107 > 3 conditions (78.1 %)

SF-36

2 years

7.2 % lost to follow up

Quality of Life (QoL) decreases as number of conditions increases

The presence of each condition associated with significantly lower SF-36 scores (except heart bypass, stroke and diabetes)

Data not shown

Drewes

2011 Netherlands

General population

(Leiden 85–plus study)

594 adults aged 85 years

MM ≥2 chronic diseases at age 85 years

Chart confirmed presence of 9 common conditions pre-specified

234 ≥ 2 chronic diseases (39.4 %)

Groningen Activity Restriction Scale

5 years

53.9 % loss to follow up

Participants with MM had an accelerated progression of ADL (activities of daily living) disability over time compared to those without MM (95 % CI 0.21 -0.63, p < 0.001)

MM demonstrated accelerated increase in ADL disability in older people with optimal cognitive function (95 % CI 0.39-0.95, p < 0.001)

This was not observed in participants with lower MMSE scores.

Kiely

1997

USA

Community based

(Sample first drawn 1982: Massachusetts state-supported home care programme)

1060 adults aged ≥65 years

No definition of MM reported

Self-report of 5 pre-specified medical conditions

MM numbers not reported

Functional Dependency Index

(FDI)

3 years

22.5 % loss to follow up

Each additional medical condition resulted in a significant increase in the FDI score (p < 0.001)

Rate of decline did not differ by total number of medical conditions (p =0.67)

Nikolova

2011 Canada

Community based

(Research Program on Integrated Services for the Elderly)

1164 disabled adults

≥65 years

Disability status estimated using the Functional Autonomy Measurement System (SMAF)

Score ≥10 excluded

Comorbidity : number of chronic diseases

Self-report of comorbidities using 16 item questionnaire

Diseases not specified but grouped into four categories:

0-1 disease

2-3 diseases

4-5 diseases

≥6 diseases

1084 ≥ 2 diseases (93.1 %)

Functional status measured using 7 item IADL subscale of the OAR and Katz ADL index

3 years

High rate of attrition discussed but loss to follow up number NR

Comorbidity burden is a strong predictor in developing IADL and ADL disability

6 diseases vs 0–1 disease

OR (95 % CI)

IADL 6.42 (1.52; 27.18)

ADL 16.73 (3.08; 91.06)

4 –5 diseases vs 0–1 disease

OR(95 % CI)

IADL 1.20 (0.52; 2.80)

ADL 0.89 (0.26; 2.98)

2–3 diseases vs 0 –1 disease

OR(95 % CI)

IADL 1.00 (0.46; 2.20)

ADL 1.44 (0.49; 4.15)

≥6 morbidities-6 times more likely to develop ADL disability and 17 times more likely to develop IADL disability

Prior

2011

UK

Primary care

4672 adults aged ≥50 years

Comorbidity –number of chronic diseases

Record confirmed condition counts over previous 2 years

In addition to number of GP consultations for morbidity in 2 year period

Specific cardiovascular and musculoskeletal conditions (n = 15) chosen as most prevalent in developed countries

Stage of disease as proxy for severity

561 ≥ 1 CVD & MSK condition

MM in overall group not reported

SF-12 (PCS)

3 years

46 % loss to follow up

Cardiovascular cohort: higher comorbidity and increasing severity in disease associated with greater deterioration in PCS.

Significant deterioration shown for HTN (p < 0.001) with PCS score deteriorating by -0.86 over three years

Musculoskeletal cohort: no association

Rigler

2002 USA

Community based

(Veteran’s Affairs Medical Centre)

492 adults aged ≥65 years

Comorbidity scores: based on sum of the domains affected, and the sum of the domains which patients reported affected function.

Self-report of 18 prevalent conditions from 8 organ domains via self-report

335 ≥ 2 diagnoses (68.1 %)

MOS-36

Physical Function Index

Self-report ADL and IADL

1 year

7.2 % loss to follow up

Increasing comorbidity significantly associated with increased risk of future functional decline

(p <0.001)

OR 1.09: 2 conditions

OR 2.41: ≥ 3 conditions

Presence of ADL and IADL problems at baseline demonstrated to have a significant impact on new ADL problems developing at one year (p <0.001)

OR 4.77: 1 IADL problem at baseline

OR 15.6: 1 ADL problem at baseline