There is significant heterogeneity in clinical phenotype and many potential comorbidities such as attention problems, impulsivity, notable responses to sensory input, oppositional behaviors, depression, feeding and sleeping differences, fears or anxieties, cognitive delays, and epilepsy and other health problems (APA, 2013; Bryson et al., 2008; Lord and Spence, 2006).
For example, the number and severity of comorbidities may have caused selection bias: patients with very severe COPD and many comorbidities (cardiovascular and musculoskeletal such as osteoporosis) might have already died, or were not able to participate in the studies due to severely limited functional capacity.
35 Frail elderly people, many of whom have other comorbidities such as osteoporosis, may be particularly vulnerable to bone fractures following a fall.
The selective study of the impact of hypovolaemic shock and fluid loading is difficult in ICU patients, who have many comorbidities that can affect caspofungin pharmacokinetics, such as renal insufficiency, need for dialysis, widely variable albumin levels and concomitant medications.
Whilst many patients with SSD have other comorbidities such as cannabis misuse [ 31], given the higher stability of schizophrenia diagnosis over time [ 32], we chose this category as the first in our hierarchical system.
Many patients with OA are elderly with comorbidities such as CV disease.
In addition, many children with autism have some medical comorbidities such as Down's syndrome, Fragile X syndrome, epilepsy, and/or tuberous sclerosis.
In addition, many patients with Gouty Arthritis have underlying comorbidities such as cardiovascular disease, diabetes mellitus, hypertension, liver and renal disease, or gastrointestinal problems, which restrict treatment options or necessitate modifications in the management of Gouty Arthritis [ 8, 11- 14].
Many patients with OA also commonly experience multiple comorbidities, such as cardiovascular, gastrointestinal, and endocrine disorders [ 4, 5].
Both Charlson and Elixhauser measures consist of chronic diseases and their prevalence may not vary much in such a short period as our findings of similar frequencies for many comorbidities across two databases.
