“Prescribing sunshine”: a national, cross-sectional survey of 1,089 New Zealand general practitioners regarding their sun exposure and vitamin D perceptions, and advice provided to patients

BACKGROUND: The health effects of ultraviolet radiation vary according to wavelength, timing and pattern of exposure, personal characteristics and practices. Negative effects include skin cancers, eye diseases and immune suppression; positive effects primarily relate to endogenous vitamin D production which protects against bone disease. Drafting comprehensive guidelines regarding appropriate sun protective behaviours and vitamin D sufficiency is challenging. Advice given by general practitioners is potentially influential because they are widely respected. METHODS: A survey instrument was developed, pre-tested and provided to practising GP’s, either by on-line link or mailed, reply paid hard-copy. Odds ratios, differences in means, or ratios of geometric means from regression models are reported for potential predictor variables with 95% confidence intervals. RESULTS: Data (demographic, training, practicing, information accessing, confidence in vitamin D knowledge) suitable for analysis were obtained from 1,089 GPs (32% participation). Many (43%) were ‘not at all confident’ about their vitamin D knowledge. Recent information led 29% to recommend less sun protection during winter months and 10% less all year. Confidence was positively associated with non-‘Western’ medical training, information sources read and practising in a metropolitan centre with a medical school. Reading the Melanoma Clinical Practice Guidelines was associated with lower estimates of the amount of summer sun exposure required to obtain adequate vitamin D. Increasing years in practice was negatively associated with provision of recommended advice about summer and winter sun protection. Greater concern about vitamin D than skin cancer was expressed by females and those in practice longer. CONCLUSIONS: Concern about the potentially negative impact of skin cancer prevention on vitamin D status may undermine appropriate sun protective recommendations. Reading some educational resources was associated with confidence about vitamin D knowledge and a perception that significantly less summer sun exposure was required for those with high sun sensitivity to achieve adequate vitamin D, suggesting a potentially positive impact of such resources. Education could be targeted towards groups least likely to promote existing recommendations. Authoritative guidelines about vitamin D and sun protection would be a valued resource among GPs. Study findings are potentially valuable to help guide public policy and target interventions.