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Table 2 Included Cohort Studies

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

Population and setting Definition and prevalence of multimorbidity (MM) Functional decline outcome measure/s Follow-up period
Losses to follow-up (%)
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
2 years
7.5 % loss to follow-up
Disability and frailty was not associated with MM over two years.
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)
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 %)
(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)
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
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.
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
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)
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
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
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 %)
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