Table 2.

State-based details for medical record review of charts uniquely assigned ‘unspecified injury of head’ International Classification of Disease, Tenth Revision, Clinical Modification S09.90 code

Characteristic	Maryland	Kentucky	Colorado	Massachusetts
Dates	January 2016–December 2018	January 2016–June 2018	January 2017–December 2017	October 2015–September 2016
Type of hospital	Large teaching hospital*	Tertiary care and community hospital	All acute care hospitals	All acute care hospitals
Number of sampled hospitals	2	2	54	73
% of state population covered by sampled hospitals	14.5%†	38%	100%	100%
Number of diagnosis fields	30	25	30	34
Medical record reviewer	18 clinical researchers	2 trauma nurses	1 professional coder	3 professional coders

*Maryland reviewed records from emergency department visits and a shock trauma centre.

†Maryland calculated the percentage of patient records corresponding to the two sampled hospitals out of the total records in a year within their healthcare administrative database.