Table 2. Measurements of Physical Impairment^*.

Papers with any assessment of physical structure or function impairment	1970 - 2013	1970 - 1999	2000 - 2013
	N = 38	N = 13	N = 25
Any pulmonary impairment measurement	32 (84%)	12 (92%)	20 (80%)
Papers using >1 test to assess pulmonary impairment	30 (94%)	10 (83%)	20 (100%)
Article to instrument ratio†	4.0	2.0	2.5
Tests used to assess pulmonary impairment
Forced Expiratory Volume in 1 Second (FEV1)	31 (97%)	11 (92%)	20 (100%)
Forced vital capacity (FVC)	29 (91%)	9 (75%)	20 (100%)
Carbon Monoxide Diffusion Capacity (DLCO)	24 (75%)	7 (58%)	17 (85%)
Total Lung Capacity (TLC)	21 (66%)	5 (42%)	16 (80%)
Other spirometry measures	19 (59%)	6 (50%)	13 (65%)
Other lung volumes	7 (22%)	2 (17%)	5 (25%)
Other pulmonary tests‡	2 (6%)	0 (0%)	2 (10%)
Any neuromuscular impairment measurement	7 (18%)	1 (8%)	6 (24%)
Papers using >1 instrument to assess neuromuscular impairment	3 (43%)	0 (0%)	3 (50%)
Article to instrument ratio	1.4	1.0	1.2
Instruments used to assess neuromuscular impairment
Electromyography/Nerve Conduction Studies (EMG/NCS)	4 (57%)	1 (100%)	3 (50%)
Manual Muscle Testing (MMT) using Medical Research Council (MRC) score	3 (43%)	0 (0%)	3 (50%)
Grip Strength	2 (29%)	0 (0%)	2 (33%)
Other neuromuscular tests‡	2 (29%)	0 (0%)	2 (33%)

^*No study included data on pre-hospitalization assessment of structure and function

^†The article to instrument ratio is the quotient of the number of articles to the number of unique measurement instruments. A higher ratio indicates greater consolidation around a core set of measures.

^‡Represents an instrument used in only 1 eligible article