This audit revealed that after three years of work IPMC had attempted a Health Assessment of the vitamin D status in 51% of patients aged 45 to 49 years. Although half of these patients had their weight measured, only 28% had a test to measure 25-OHD.
The audit revealed a bias towards testing patients who had low or borderline 25-OHD. This suggests that the 25-OHD test was not used as a screening tool; rather it was used for case finding. Knowledge of a patient's low 25-OHD appeared to have little impact on changing the patient's level. Only 8% of such patients were subsequently shown to revert back to normal levels.
The overall mean 25-OHD level (74.0 nmol/l) found in this audit was similar to the 76.9 nmol/l mean level found in a group of Adelaide residents[4
] and higher than the 56.8 nmol/l mean level found in a recent study of adult Aboriginal Australians[5
]. Furthermore, the audit confirmed the known seasonal variation in 25-OHD [5
] by finding a high proportion of 25-OHD tests taken in summer compared to other seasons and a comparatively low proportion of patients with low levels of 25-OHD in summer. In our audit, we did not measure the amount of time patients spent outside. Therefore we can only speculate that the paradoxical relationship between a high proportion of testing undertaken in summer and a low proportion of patients with low levels of 25-OHD in summer is a consequence of patient behaviour - perhaps patients spend less time outside in response to high temperatures in the ACT in the summer months.
The audit revealed a gender imbalance: Women were more likely to have a health assessment than men and consequently were more likely to have a test. However, women were also found to have significantly lower 25-OHD level than men. Furthermore, men were significantly heavier and had larger waists than women, but no difference in BMI or activity scores. These differences suggest that men and women need different practice policies for health promotion.
The audit demonstrated that sending uninvited health promotion information to patients had no effect on subsequent attendance for health promotion in this practice. New health promotion strategies are needed. For example, sending a newsletter to the whole practice population, or working in conjunction with the local media, might stimulate more people to consider the relationship between vitamin D and the amount of sunlight exposure they experience. The RACGP guidelines for preventive activities in general practice list the strategies that Australian general practice might undertake for health promotion and mentions vitamin D [1
]. The guidelines do not mention how practices might vary their strategies in response to specific characteristics such as the gender profile of the general practice.
The limitations of this clinical audit include the bias of using only one general practice, the non-random selection of patients, the local laboratory determined the normal serum 25-OHD reference range, and the measurement error inherent in undertaking an audit. (In Australian general practice patients may go elsewhere to manage their low 25-OHD and there are limited mechanisms to ensure patients comply on follow up of low-test results). Finally we did not measure the amount of sunlight exposure in patients.
In summary, a considerable amount of work was undertaken by IPMC over three years resulting in half the target group of patients receiving health promotion, just over a quarter had the appropriate blood test, and none were influenced by uninvited written health information on vitamin D. The audit taught IPMC that men and women need different policies for health promotion on the association between 25-OHD levels and time spent outside in summer.