Limitations of the Wells Score
A meta-analysis of 51 studies has shown that the overall assessment of clinical probability of DVT by use of the Wells score is more useful than any of the individual components comprising the score, with a negative likelihood ratio (0.25, 95% CI 0.21-0.29) similar to that of an empirical assessment.
Nevertheless, when the population to be assessed contained a large percentage of elderly patients or those with a prior DVT or other comorbidities, as might occur in a primary care setting, the performance of the Wells criteria was reduced.
Therefore, it seems prudent that the Wells criteria are used to complement rather than displace the clinician's empirical assessment.