If there is no issue number, place the colon after the volume number as in the example below.
Example:
Hex N, Bartlett C, Wright D, Taylor M, Varley D. Estimating the current and future costs of Type 1 and Type 2 diabetes in the UK, including direct health costs and indirect societal and productivity costs. Diabetic Medicine. 2012; 29:855–62. Table 1, Estimated UK prevalence of diabetes 2010 ⁄ 2011 and 2035 ⁄ 2036; [cited 2013 Jul 22]; p.858. Available from: http://onlinelibrary.wiley.com/doi/10.1111/j.1464-5491.2012.03698.x/pdf