TABLE 1.
Characteristics of the included studies
| Study | Country | Design | Participant characteristics | Sample size | Mean age (years) | Men (%) | Diagnosis of insomnia | No. of people with insomnia | Diagnosis of frailty | No. of people with frailty | Variables adjusted |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Vaz Fragoso et al. (2009) | USA | CS | Community‐living old people ≥75 years | 374 | 84.3 | 32.6 | ISI | 160 | FFP | 154 | Age, sex, cognitive impairment, comorbidities, depressive symptoms, and concomitant medications |
| Ensrud et al. (2009) | USA | CS | Community‐derived old men ≥67 years | 3133 | 76.4 | 100 | PSQI | 1383 | CHS frailty index | 437 | Age, race, site, health status, educational level, social support, alcohol intake, smoking status, depressive symptoms, cognitive function, functional disabilities, BMI, and concomitant medications |
| Devkota et al. (2017) | Nepal | CS | Community‐derived old people ≥60 years | 253 | 79.1 | 32 | Self‐reported | 123 | CSHA frailty tool | 70 | Age, sex, smoking, living arrangements, and comorbidities |
| Moreno et al. (2017) | Mexico | CS | Community‐living old people ≥60 years | 591 | 76.3 | 47.2 | Self‐reported | 118 | FFP | 63 | Age, sex, ethnicity, education, cognitive status, daily activity, physical performance, and concomitant medications |
| Zhao et al. (2019) | China | CS | Older adults (≥60 years) in nursing homes | 370 | 77.6 | 40.5 | AIS | 169 | FRAIL scale | 108 | Age, sex, ethnicity, education, depression, and daily activities |
| Pacholek et al. (2020) | Poland | CS | Community‐derived old people ≥65 years | 438 | 75.6 | 37 | AIS | 182 | CFS | 144 | Age, sex, living condition, daily activity, cognitive status, and concomitant medications |
| Xie et al. (2021) | China | CS | Community‐living old people ≥75 years | 1585 | 81.4 | 41.8 | Self‐reported | 731 | FFP | 225 | Age, sex, education, marital status, depression, comorbidity, and concomitant medications |
| Liu et al. (2021) | USA | CS | Community‐derived old people ≥65 years | 7609 | 74.2 | 43.5 | Self‐reported | 2278 | FFP | 1065 | Age, sex, pain, and depression |
| Moreno‐Tamayo et al. (2021) | Mexico | CS | Community‐living old people ≥60 years | 1643 | 67.1 | 50.1 | AIS | 497 | FFP | 172 | Age, sex, education, married/civil union, current alcohol consumption, current smoking, clinically significant depression symptoms, cognitive decline, comorbidities, and concomitant medications |
| Tang et al. (2021) | China | CS | Community‐living old people ≥65 years | 345 | 80.3 | 20 | PSQI | 195 | FRAIL scale | 140 | Age and sex |
| Cavusoglu et al. (2021) | Turkey | CS | Community‐derived old people ≥80 years | 100 | 83.5 | 45 | PSQI | 58 | FFP | 41 | Age, sex, daily activity, and comorbidities |
| Fan et al. (2022) | China | CS | Community‐living old people ≥60 years | 454 | 69.1 | 42.3 | AIS | 211 | TFI | 185 | Age, sex, marital status, residence, monthly personal income, level of education and comorbidity |
Abbreviations: BMI, body mass index; CS, cross‐sectional; CFS, Clinical Frailty Scale; ISI, Insomnia Severity Index; FFP, fried frailty phenotype; PSQI, Pittsburgh Sleep Quality Index; CHS, Cardiovascular Health Study; CSHA, Canadian Study of Health and Aging; AIS, Athens Insomnia Scale; TFI, Tilburg Frailty Indicator.