Elastic compression stockings: Durability of pressure in daily practice

Background: Elastic compression stockings are valuable tools in the treatment of many phlebological diseases. As to day no data are available about how long these elastic compression stockings continue to exert enough compression for a proper clinical function. Patients and methods: In this study we measured the pressure at the B level of compression class II and III elastic stockings directly after the patients started to use them, after I month, and after 3 months. In total 99 below knee stocking were measured with a TNO-tester, which has officially been accepted by the CEN for measurement of elastic compression stockings. Results: Class II flat knitted stockings showed a mean pressure of 29.3 (SD 4.9) mmHg at the start of the study, declining to 27.6 (SD 5.2) mmHg, and 26.5 (SD 4.4) mmHg, at 1 and 3 months respectively. The round knitted class II had comparable results. In class Ill fiat knitted stockings we measured 47.5 mmHg (SD 8.1) at the start, and 44.2 (SD 7.1) mmHg, and 41.3 (SD 6.7) mmHg, at 1 and 3 months respectively. Extrapolation of the results after 1 and 3 months demonstrate that the mean pressure of class II stocking is less than 25 mmHg after 4 to 5 months. Class III stockings were less than 35 mmHg close to 6 months, if evaluated in the same way. Individual regression analysis show that after 6 months 66% of the pressure class II stockings have a pressure of less than 25 mmHg and 45% of the pressure class III less than 35 mmHg. When considering a 10% safety margin the figures are respectively 84% and 63%. Conclusions: From the results of this study it can be concluded that, especially for the most frequently used compression class II stockings, three new stockings each year are necessary to ensure an effective function of the stocking daring the time they are being used by the patient. For compression class III fiat knitted stockings two pairs can be considered as sufficient.