Health-related Quality of Life Scale Measure Considerations

SF-36 Scales Measures

SF-36 Scales Measures (adopted from: Jones, et. al. Health and Quality of Life Outcomes 2004)
Scale	Description
Physical Component Summary (PCS)	Summary measure which included: PF, RP, BP, VT, SF, RE, MH and GH
Physical functioning (PF) (Survey Items 3a through 3j)	Ten questions asking for ratings of the extent to which the respondent's health limits them in their performance of physical activities.
Role-physical (RP) (Survey Items 4a through 4d)	Four questions asking the extent to which the physical health of the person completing the scale limits them in their work or other usual activities in terms of time and performance.
Bodily pain (BP) (Survey Items 7 and 8)	Two questions asking for the severity of pain experienced by the respondent and for the extent to which pain interferes with normal work, including work outside the home and housework.
General health (GH) (Survey Items 1, and 11a through 11d)	5 questions that ask the individuals to rate their current health status overall, their susceptibility to disease, and their expectations for health in the future.
Mental Component Summary (MCS)	Summary measure which included: MH, RE, SF, VT, GH, BP, RP, and PF.
Vitality (VT) (Survey Items 9a, 9e, 9g and 9i)	Four questions asking for subjective well-being ratings in terms of energy and fatigue
Social functioning (SF) (Survey Items 6 and 10)	2 questions on limitations in normal social functioning due specifically to health-related problems.
Mental Health (MH) (Survey Items 9b, 9c, 9d, 9f and 9h)	5 questions about the frequency of feelings representing the 4 major mental health dimensions.
Role-emotional (RE) (Survey Items 5a, 5b and 5c)	3 questions about whether emotional problems have interfered with accomplishments at work or other usual activities in terms of time, as well as performance.

What aggregate measures of the SF-36 and VR-12 Measures are available?

Aggregated measures of the 8 scales and summary scores (PCS and MCS) of the SF-36 and VR-12 are provided in the SEER-MHOS data resource. Each of the 8 scale measures are available as both a raw score and a T-score for all MHOS eras (SF-36 and VR-12). The T-scores are a linear transformation of the 0-100 possible range scoring for the SF-36/VR-12 scales that gives every scale a mean of 50 and standard deviation of 10, normed to the US general population. For analyses that use the bridging algorithm to pool data from both eras, it is important to use the PCS12 and MCS12 summary measures which use imputation methods to account for missing data on items and therefore cannot be transformed to a T-score metric. The PCS12 and MCS12 measures have similar properties to the PCS_T and MCS_T summary metrics, however:

	PCS_T (1990 Norms)		PCS12
	HOS 1.0	HOS 2.0	HOS 1.0	HOS 2.0
Mean	38.33	37.48	37.88	37.27
SD	12.07	12.39	12.18	12.38
25% Percentile	28.45	27.51	27.93	27.8
Median	38.61	37.62	37.85	37.95
75% Percentile	48.9	48.13	48.76	47.72
Min	3.45	3.13	-0.27	-0.22
Max	68.43	75.43	66.19	70.84

	MCS_T (1990 Norms)		MCS12
	HOS 1.0	HOS 2.0	HOS 1.0	HOS 2.0
Mean	51.19	50.41	50.39	50.31
SD	10.74	12.12	10.91	11.85
25% Percentile	44.28	42.38	42.67	42.53
Median	54.42	53.24	53.28	53.23
75% Percentile	59.33	59.96	59.24	59.76
Min	6.42	-4.58	3.19	-1.56
Max	77.09	79.08	73.7	75.89

Overall measure of health: the VR-6D

In general, the PCS and MCS are widely recognized independent, aggregate measures of physical and mental health, respectively. Another measure, called the VR-6D, is a health utility metric that ranges from 0-1 and is based upon the SF-6D originally developed by John Brazier of the University of Sheffield, UK. Investigators may want to consider using this measure if they wish to summarize the overall health of the participants in their study.

For more information, see:

Selim AJ, Rogers W, Qian SX, Brazier J, Kazis LE. A preference-based measure of health: the VR-6D derived from the veterans RAND 12-Item Health Survey. Qual Life Res 2011 Oct;20(8):1337-47. doi: 10.1007/s11136-011-9866-y. [View Abstract]