The SF-36v2 and SF-12v2 health surveys in New Zealand: norms, scoring coefficients and cross-country comparisons

Objective: To provide New Zealand population norms for version 2 of the SF-36 and SF-12 health surveys and report scoring coefficients that enable the construction of Physical and Mental Component Summary scores from New Zealand SF-36v2 and SF-12v2 data. Approach: Norms for the SF-36v2 and scoring coefficients for the Physical and Mental Component Summary scores are estimated using 2006/07 New Zealand Health Survey data, which included 12,488 adults (aged 15 years and over). Norms for the SF-12v2 are derived from 2008 New Zealand General Social Survey data, including 8,721 adults. Comparisons are made between New Zealand norms for versions 1 and 2 of the SF-36 instrument. In addition, New Zealand SF-36v2 and SF-12v2 norms and the scoring coefficients are compared with those for the United States and South Australia. Conclusion: Differences between: 1) New Zealand population norms for the SF-36 versions 1 and 2; and 2) SF-36v2 and SF-12v2 population norms for New Zealand and those for the United States and South Australia highlight the importance of using version-specific and country-specific population norms. Implications: The analysis reported here allows for the appropriate use of the SF-36v2 and SF-12v2 instruments in New Zealand.