The phrase "as their index" is correct and usable in written English.
It can be used in contexts where you are referring to something that serves as a reference point or measure for a group or set of items.
Example: "The researchers used the average temperature as their index to determine climate change effects."
Alternatives: "as their reference" or "as their benchmark".
Inducible patients were more likely to have coronary artery disease, previous infarction, and VT as their index arrhythmic event.
An additional four studies used clinical variables, PCR, and CRP as their index tests.
We assigned the date of their first-time diagnosis of BC as their index date.
For unexposed men, follow-up started at the same date as their index man.
In normocalcaemic participants, the date of their first calcium test was assigned as their index date.
People with hypoglycaemia were also more likely to have initiated a sulphonylurea as their index drug (Table 1).
Our case was not based upon the number of people in what could loosely be described as their "indices".
Furthermore, many of the indicators as well as their indices geared toward innovation and economic growth are incomplete, not addressing the intangibility of innovation, and lacking in detail and timeliness (Still et al. 2013b).
Patients were excluded from the study sample if they: (1) had incomplete data during pretreatment or follow-up; (2) received Viagra during pretreatment; (3) were aged <18 years as of their index date; or (4) were aged ≥65 years as of their index date if they were not enrolled in a Medicare risk-sharing (i.e., capitated) plan.
To account for changes in the age distribution at 1 year of follow-up, VTE rates for the 2 5 year survivor cohort were standardised to the age distribution of patients with BC as of their index dates.
Mixed material thin films are used in gradient index optical systems as their refractive index can be tailored to meet requirements.
