4 Models of Compression Hosiery found a Wide Discrepancy between Actual and Claimed Compression Values Effectiveness of 3 Models in Improving Blood Circulation in Doubt

15 May 2019
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People who need to stand for long periods in their job, people who are plump, pregnant women and elderly are vulnerable to the formation of varicose veins on their calves.  The Consumer Council tested 10 models of palliative compression hosiery and found a considerable difference in performance.  3 models were found to be likely ineffective in improving blood circulation; and 7 models did not provide detailed information on measurements, which is vital for consumers to choose the correct size.  Discrepancies were detected in 5 models between the actual test fibre content and the claimed content; 2 models with the most serious discrepancies were subsequently referred to the Customs and Excise Department for follow-up action.

Compression hosiery boosts blood flow from the lower limbs, thus reducing pressure on the lower limb veins and vein valves, so as to prevent varicose veins or prevent the symptoms from getting worse.

According to the International standards, compression hosiery products are based on compression levels at the ankle, categorised into 4 classes: low, medium, medium high and high.  The latter two are suitable for patients with a serious varicose vein condition; they should be diagnosed and prescribed by healthcare professionals for purchase and use. The low and medium type are for preventive purposes, generally provide a compression level of 25mmHg or below.  Included in the test were 10 preventive compression hosiery models with claimed compression values between 18 and 25.5mmHg, comprising 7 below-the-knee stockings and 3 pantyhose models ranging in price from $139 to $468.

The test focused on their compression performance, durability and comfort, as well as the accuracy of their fibre composition label.  The results revealed a significant variation in the overall performance ratings of the models – from 1 to 5 points.  1 of the cheaper models ($148) was awarded the top rating of 5 points.  In contrast, one of the most expensive models ($468) scored only 3 points, which shows price and quality are not necessarily correlated. 

The test found that the discrepancy between the measured average compression value and the claimed value at the ankle of 4 models were from 22.5% to 49.9%, exceeded the upper limit (not more than 20%) of the standard requirement BS 661210. In the worst case, one pantyhose model was measured with an average compression value at the calf and thigh that was lower than the claimed value by 43% and 60%, respectively, its actual performance was doubtful.

Compression hosiery is designed to exert the greatest degree of compression at the ankle, with the level of compression gradually decreasing towards the knee to ensure that the blood flows upwards.  According to the standard requirement, the compression level at the calf should be 50% to 85% of ankle compression; likewise, the compression at the thigh should be 50% to 85% of the calf compression.  But in 3 models, calf compression was only 88.8% to 90.4% of ankle compression, so the compression proportion did not comply with the standard, and with so small difference in the compression level between the ankle and calf, the hosiery may not effectively push the venous blood flow upwards.  In 1 of the models, thigh compression was 35.3 % of the calf compression, which is lower than the standard requirement.  This means that though the venous blood may be pushed upwards from the calf to the thigh, the compression at the thigh is too low that cannot effectively improve the recirculation of venous blood flow.

Appropriate measurements of compression hosiery are equally important in delivering the right effect.   Of the 10 models tested, 7 failed to provide vital information about ankle, calf, thigh and hip girth, which may result in consumers purchasing hosiery that doesn’t fit well – that is too tight, difficult to wear, uncomfortable or too loose – so it will not achieve the optimal result.  Also, 1 model was not even labelled with the compression value, so consumers have no way of knowing if the product compression is suitable for their needs. 

In the durability test, all models were washed and dried 50 times.  The results showed shrinkage to various degrees in all models, with 1 model shrinking by 15.2% in the length of stockings.  In 1 model, the compression value at the calf and thigh increased by 35% and 25% after washed, respectively, and in another model, the thigh compression value jumped by 40%, far exceeding the reference standard requirement that the discrepancy before and after washing should not exceed 15%.  Although shrinkage or increase in compression of hosiery resulted from multiple washings may not affect its performance, it might become so tight that is difficult to wear or uncomfortable when wearing.

In 1 model, the proportion of ankle compression at calf reached 108.6% after multiple washings, indicating that the compression value at the calf was greater than that at the ankle, making it like a “haemostatic arterial tourniquet”, affecting blood circulation.

Moreover, the test detected a discrepancy of fiber composition in 5 models that the actual content varied about 5% to 21% to the claimed value.  The fiber label on 2 of the models was particularly inaccurate; both were labelled with polyester and elastane/polyurethane, but the actual content turned out to be nylon and elastane/polyurethane.  The findings were forwarded to the Customs and Excise Department for further action.

The Council recommends the following useful tips for choosing and buying compression hosiery:

- Choose the compression level and style that best suits the severity of your condition. Tight compression hosiery is not necessarily better, too much compression may even backfire by restricting blood circulation;  

- Measure your ankle, calf and thigh carefully for girth and length, before choosing the appropriate size of hosiery.  If you experience itchiness, pain or a rash, or if your legs feel tired or cold, stop wearing the hosiery;

- Compression hosiery generally comes in knee- or thigh-length stockings or pantyhose.  The knee-length stockings are generally sufficient to boost blood flow in the lower limbs.  For women who need to wear skirts, pantyhose is a better choice, as it fits more securely;

- For eczema patients and those who are prone to skin irritation or allergic reaction to clothing, it is recommended to choose hosiery with cotton-based fabrics and not dyed in dark colours;

- The ideal time to wear compression hosiery is in the morning after you get up, as the blood vessels in the legs have not yet expanded.  It’s not advisable to wear hosiery to sleep at night because your legs and heart are on the same plane, so even without compression, the blood in the legs will naturally flow back to the heart;

- If you have diabetes, dermatitis or other blood disorders, or if you are older, wearing compression hosiery may slow down blood flow due to comparatively weak blood circulation, which may cause muscle necrosis, so consult a doctor before use.

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