Table 1 The baseline characteristics of the patients stratified by their number of rare diseases

Number of patients per group

146,804

17,051

2053

Demographics

Age groups (%)

 18–34

36,084 (24.6)

2280 (13.4)

291 (14.2)

 35–49

32,924 (22.4)

2905 (17.0)

382 (18.6)

 50–64

31,883 (21.7)

4679 (27.4)

593 (28.9)

 65–79

31,417 (21.4)

5160 (30.3)

615 (30.0)

 80 and older

14,496 (9.9)

2027 (11.9)

172 (8.4)

Sex = M (%)

67,557 (46.0)

9437 (55.3)

1179 (57.4)

Diagnosis count, excluding rare diseases (median [IQR])

4.00 [2.00, 7.00]

5.00 [3.00, 9.00]

8.00 [4.00, 13.00]

Rare diseases

Certain infectious and parasitic diseases (%)

0 (0.0)

516 (3.0)

192 (9.4)

Neoplasms (%)

0 (0.0)

3035 (17.8)

590 (28.7)

Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (%)

0 (0.0)

609 (3.6)

159 (7.7)

Endocrine nutritional and metabolic diseases (%)

0 (0.0)

1772 (10.4)

467 (22.7)

Mental and behavioural disorders (%)

0 (0.0)

22 (0.1)

6 (0.3)

Diseases of the nervous system (%)

0 (0.0)

3357 (19.7)

574 (28.0)

Diseases of the eye and adnexa (%)

0 (0.0)

401 (2.4)

49 (2.4)

Diseases of the ear and mastoid process (%)

0 (0.0)

169 (1.0)

30 (1.5)

Diseases of the circulatory system (%)

0 (0.0)

1551 (9.1)

393 (19.1)

Diseases of the respiratory system (%)

0 (0.0)

210 (1.2)

57 (2.8)

Diseases of the digestive system (%)

0 (0.0)

655 (3.8)

234 (11.4)

Diseases of the skin and subcutaneous tissue (%)

0 (0.0)

307 (1.8)

56 (2.7)

Diseases of the musculoskeletal system and connective tissue (%)

0 (0.0)

1659 (9.7)

280 (13.6)

Diseases of the genitourinary system (%)

0 (0.0)

78 (0.5)

4 (0.2)

Pregnancy childbirth and the puerperium (%)

0 (0.0)

167 (1.0)

6 (0.3)

Congenital malformations, deformations and chromosomal abnormalities (%)

0 (0.0)

1958 (11.5)

460 (22.4)

Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (%)

0 (0.0)

585 (3.4)

162 (7.9)

Outcomes

Number of patients who died in hospital (%)

3202 (2.2)

1082 (6.3)

262 (12.8)

30-day readmission (%)

 No

137,918 (93.9)

15,364 (90.1)

1819 (88.6)

 Unknown

1768 (1.2)

215 (1.3)

29 (1.4)

 Yes

7118 (4.8)

1472 (8.6)

205 (10.0)

Length of stay in days (median [IQR])

5.00 [3.00, 8.00]

7.00 [4.00, 14.00]

11.00 [5.00, 20.00]

ICU admissions (%)

16,178 (11.0)

3987 (23.4)

763 (37.2)

Total time spent in ICUs in days (median [IQR])

0.00 [0.00, 0.00]

0.00 [0.00, 0.00]

0.00 [0.00, 2.00]

Total time spent in ICUs in days (mean (SD))

0.44 (2.70)

1.45 (5.63)

3.59 (9.39)