Table 3.
Pooled comorbidity proportion by study type
| Associated condition category | Associated condition | Population studies (52 studies) | Clinical studies (87 studies) | Heterogeneity between Groups |
|---|---|---|---|---|
| Cancers | Any cancer | 3 % (3–3 %) | 2 % (0–5 %) | p = .131 |
| Cardiovascular diseases | Ischemic heart disease | 8 % (5–11 %) | 5 % (2–10 %) | p = .293 |
| Stroke/Cerebrovascular | 4 % (3–7 %) | 6 % (3–9 %) | p = .241 | |
| Hypertension | 26 % (24–29 %) | 19 % (14–26 %) | p = .061 | |
| Atrial fibrillation and flutter | 1 % (0–2 %) | 2 % (0–9 %) | p = .479 | |
| Digestive diseases | Upper digestive system diseases | 17 % (16–18 %) | 8 % (2–18 %) | p = .086 |
| Irritable bowel syndrome | – | 19 % (1–53 %) | – | |
| Metabolic and kidney diseases | Diabetes mellitus | 6 % (4–7 %) | 7 % (3–12 %) | p = .281 |
| Chronic kidney disease | 4 % (0–13 %) | 0 % (0–1 %) | p = .097 | |
| Obesity | 18 % (13–24 %) | 25 % (16–35 %) | p = .203 | |
| Hyperlipidemia | 17 % (8–29 %) | 13 % (9–19 %) | p = .543 | |
| Hypercholesterolemia | 29 % (13–49 %) | 15 % (9–22 %) | p = .137 | |
| Thyroid diseases | 3 % (3–3 %) | 16 % (7–27 %) | p < .001 | |
| Musculoskeletal disorders | Arthritis | 19 % (15–23 %) | 6 % (0–15 %) | p = .028 |
| Back pain | 54 % (53–55 %) | 48 % (11–86 %) | p = .774 | |
| Fibromyalgia | 1 % (1–1 %) | 31 % (20–44 %) | p < .001 | |
| Neurological disorders | Parkinson disease | 1 % (1–2 %) | – | – |
| Idiopathic epilepsy | 2 % (1–2 %) | 2 % (2–3 %) | p = .199 | |
| Sleep disorder | 33 % (25–41 %) | 56 % (46–66 %) | p = .001 | |
| Restless leg syndrome | 6 % (2–13 %) | 28 % (20–38 %) | p < .001 | |
| Mental health disorders | Depressive disorders | 15 % (11–19 %) | 31 % (24–38 %) | p = .000 |
| Bipolar disorder | 5 % (0–17 %) | 3 % (2–5 %) | p = .799 | |
| Anxiety disorders | 18 % (16–21 %) | 30 % (23–39 %) | p = .003 | |
| Post-traumatic stress disorder | 2 % (2–2 %) | 21 % (16–26 %) | p < .001 | |
| Respiratory diseases | Asthma | 9 % (3–16 %) | 7 % (0–27 %) | p = .839 |
| Chronic obstructive pulmonary disease | 6 % (0–21 %) | 3 % (2–4 %) | p = .489 | |
| Sense organ disease | Any sense organ diseases | – | 26 % (10–47 %) | – |
| Skin and subcutaneous disease | Any skin and subcutaneous disease | 7 % (7–7 %) | 1 % (0–3 %) | p < .001 |
| Substance use disorders | Any substance use disorder | 5 % (0–18 %) | 7 % (4–10 %) | p = .665 |
| Other NCDs | Oral disorders | – | 67 % (40–89 %) | – |
| Hemoglobinopathies and hemolytic anemias | 3 % (3–3 %) | 0 % (0–2 %) | p = .300 | |
| Other disorders (Congenital birth defects & Gynecological diseases) | 15 % (10–21 %) | 33 % (0–85 %) | p = .430 | |
| Allergies | 33 % (17–51 %) | 12 % (8–17 %) | p = .012 |