The importance of complete follow-up for results after femoro-infrapopliteal vascular surgery.
OBJECTIVE
The aim of this study was to assess the reliability of patency rates calculated on basis of data from a standard vascular registry.


METHODS
Since 1989, all patients undergoing infrainguinal bypass procedures have been offered a standard follow-up programme at 3 month intervals and all data have been recorded prospectively in a vascular registry. As part of a randomised trial on adjuvant medication in femorocrural bypass surgery, 102 patients, operated on between 1990 and 1992 were independently and simultaneously monitored. This subgroup was examined at 3 and 12 months postoperatively and 100% follow-up was obtained. After completion of the trial we calculated the patency and survival rates using life-table methods and compared the results based on the vascular registry with those achieved in the clinical trial.


RESULTS
Comparing the results from the two databases revealed a marked discrepancy between the calculated figures: primary (68% in the registry and 52% in the trial) and secondary patency rates (90% vs. 63%), limb survival (97% vs. 77% as well as patients survival rates (95% vs. 85%). The differences could be explained by a substantial number of patients being lost to follow-up according to the vascular registry database and the fact that these patients turned out to have a significantly increased rate of graft thrombosis, limb amputation and death, respectively.


CONCLUSIONS
Life-table statistics may inadvertently become unreliable if a large proportion of patients is lost to follow-up, since failure to examine the patient for any reason may be related to the patients health. In addition to the number of patients at risk, it is suggested, that life-table plots should be supplemented with information on the number of patients lost to follow-up.
Department of Vascular Surgery, National University Hospital, Rigshospitalet, Copenhagen, Denmark.
L P
LP
Jensen
O M
OM
Nielsen
T V
TV
Schroeder
D000671:Amputation, Surgical; D017024:Chemotherapy, Adjuvant; D005263:Femoral Artery / Q000473:pathology / Q000601:surgery*; D005500:Follow-Up Studies; D006083:Graft Occlusion, Vascular / Q000209:etiology; D006801:Humans; D007256:Information Systems; D007866:Leg / Q000098:blood supply; D015993:Life Tables; D010352:Patient Dropouts; D011150:Popliteal Artery / Q000473:pathology / Q000601:surgery*; D011446:Prospective Studies; D016032:Randomized Controlled Trials as Topic; D012042:Registries; D015203:Reproducibility of Results; D015996:Survival Rate; D013927:Thrombosis / Q000209:etiology; D014654:Vascular Patency; D014656:Vascular Surgical Procedures / Q000706:statistics & numerical data