Pre-admission comorbidity in 1520 patients hospitalised with pandemic H1N1 infection during the 2009–2010 pandemic compared with national prevalence data
| Underlying medical conditions | ||||
| Children (<16 years), n=480 (31.6%), n (%) | Adults, n=1040 (68.4%), n (%) | All admissions, (n=1520), n (%) | Background, prevalence in the general population,* % | |
| No. of comorbidities† | ||||
| 0 | 346 (72.1) | 492 (47.3) | 838 (55.1) | – |
| 1 | 115 (23.9) | 394 (37.9) | 509 (33.5) | – |
| 2 or more | 19 (4.0) | 154 (14.8) | 173 (11.4) | – |
| Comorbidity | ||||
| Cardiovascular disease | 20 (4.2) | 168 (16.2) | 188 (12.4) | 3.5 |
| Pulmonary disease | ||||
| COPD | 0 (0.0) | 83 (8.0) | 83 (5.5) | 1.5 |
| Asthma | 71 (14.8) | 314 (30.2) | 385 (25.3) | 5.9 |
| Other pulmonary disease | 16 (3.3) | 20 (2.0) | 36 (2.4) | – |
| Diabetes | 6 (1.3) | 96 (9.2) | 102 (6.7) | 4.1 |
| Other metabolic disease | 8 (1.7) | 4 (0.4) | 12 (0.8) | – |
| Neurological disease | 36 (7.5) | 51 (5.0) | 87 (5.7) | – |
| Cerebrovascular disease | 0 (0.0) | 5 (0.5) | 5 (0.5) | 1.7 |
| Obesity recorded on admission† | 3 (0.6) | 46 (4.4) | 49 (3.2) | 8.1‡ |
| Pregnancy | 1 | 82 (20.3)§ | 83 (20.8)§ | 5.6¶ |
↵* National prevalence data on comorbidity were obtained from the Quality and Outcomes Framework (QOF) primary care data for 2009 (http://www.qof.ic.nhs.uk) and are based on all ages, except for pregnancy.
↵† Recorded obesity and pregnancy are excluded from the number of comorbidities in the upper part of table 2.
↵‡ National prevalence data on obesity based on QOF obesity registers, defined as body mass index ≥30.
↵§ Percentage of pregnancies shown represents proportion in women aged 16–44.
↵¶ 5.6% of women aged 15–44 estimated to be pregnant in source population: in addition to 761 934 live births in the UK in 2008 (Office of National Statistics, General Register Office for Scotland and Northern Ireland Statistics and Research Agency) we assumed that 4% of women aged 15–44 years experienced a miscarriage or abortion in the same time period (500 084). To calculate the prevalence of pregnancy we took 9/12 of annual live births (assuming 9-month duration of pregnancy) and 3/12 of miscarriages/abortions (assuming 3-month duration), divided by the total female population aged 15–44 years (12 502 100).