Background: Diagnosing pigmented skin lesions in general practice is challenging. SIAscopy has been shown to\r\nincrease diagnostic accuracy for melanoma in referred populations. We aimed to develop and validate a scoring\r\nsystem for SIAscopic diagnosis of pigmented lesions in primary care.\r\nMethods: This study was conducted in two consecutive settings in the UK and Australia, and occurred in three\r\nstages: 1) Development of the primary care scoring algorithm (PCSA) on a sub-set of lesions from the UK sample;\r\n2) Validation of the PCSA on a different sub-set of lesions from the same UK sample; 3) Validation of the PCSA on\r\na new set of lesions from an Australian primary care population. Patients presenting with a pigmented lesion were\r\nrecruited from 6 general practices in the UK and 2 primary care skin cancer clinics in Australia. The following data\r\nwere obtained for each lesion: clinical history; SIAscan; digital photograph; and digital dermoscopy. SIAscans were\r\ninterpreted by an expert and validated against histopathology where possible, or expert clinical review of all\r\navailable data for each lesion.\r\nResults: A total of 858 patients with 1,211 lesions were recruited. Most lesions were benign naevi (64.8%) or\r\nseborrhoeic keratoses (22.1%); 1.2% were melanoma. The original SIAscopic diagnostic algorithm did not perform\r\nwell because of the higher prevalence of seborrhoeic keratoses and haemangiomas seen in primary care. A primary\r\ncare scoring algorithm (PCSA) was developed to account for this. In the UK sample the PCSA had the following\r\ncharacteristics for the diagnosis of ââ?¬Ë?suspiciousââ?¬â?¢: sensitivity 0.50 (0.18-0.81); specificity 0.84 (0.78-0.88); PPV 0.09 (0.03-\r\n0.22); NPV 0.98 (0.95-0.99). In the Australian sample the PCSA had the following characteristics for the diagnosis of\r\nââ?¬Ë?suspiciousââ?¬â?¢: sensitivity 0.44 (0.32-0.58); specificity 0.95 (0.93-0.97); PPV 0.52 (0.38-0.66); NPV 0.95 (0.92-0.96). In an\r\nanalysis of lesions for which histological diagnosis was available (n = 111), the PCSA had a significantly greater\r\nArea Under the Curve than the 7-point checklist for the diagnosis of melanoma (0.83; 95% CI 0.71-0.95 versus 0.61;\r\n95% CI 0.44-0.78; p = 0.02 for difference).\r\nConclusions: The PCSA could have a useful role in improving primary care management of pigmented skin\r\nlesions. Further work is needed to develop and validate the PCSA in other primary care populations and to\r\nevaluate the cost-effectiveness of GP management of pigmented lesions using SIAscopy.
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