There are commonly prescribed and administered medications that require accurate weight measurement for safe prescribing.

Weight needs to be measured using equipment that is calibrated to maintain accuracy and precision.

Do you know where the scales are on the ward? And when they are calibrated?

Accurately weighing a patient is one of the admission assessment parameters that is consistently poorly measured.

One hospital has found that there was an eighteen per cent compliance in recording patient weight accurately

Blood pressure medication, sedation, chemotherapy and anti-thrombolytic medication all require accurate weight measurement for safe prescribing and administration.

In many clinical settings the incidence of poor compliance in obtaining and recording patient weight has led to unsafe care.

The importance of accurate weight measurement is especially relevant in intensive care units, care of bariatric patients; and patients with renal impairment.

When weight was recorded, nearly 25% of staff estimated the weight of patients. 

One practice that occurs is the visual estimation of the patient’s weight. 

But over 40% of patients needed an accurate weight to have had an informed clinical decision for treatment,

Now a barrier to an accurate weight may be the clinical status of the patient. They are just too unwell to be weighed.

But a more likely explanation is the lack of access to appropriate scales that accommodate the patient.

Also the scales may not be accurate.

Where this occurred, there was a large and unacceptable variance and inaccuracy in the estimation.

There was one study that tried averaging estimates of weight by different people.

It was thought that like the “wisdom of crowds” it would lead to a more accurate weight measure.

It was unreliable.

It is not only medication where an accurate weight is important, manual handling of patients and the number of staff and required equipment, radiation therapy doses also require accurate weight recordings for safe and effective patient care.

Evans sai

“Failure to obtain an accurate weight, and re‐assessment of weight, poses significant risks and should be seen as an unacceptable practice within the healthcare team.During any admission to hospital patients, and their families, should have full confidence the right dose of medication is prescribed and administered, or other interventions are undertaken to ensure optimal recovery. Recorded weight informs the planning of safe and quality care and minimises the risks to both the patient and the care providers.”

Accurate paediatric weight is important when prescribing medication but the same emphasis of accuracy in dosage is not that evident in adults.

Safe prescribing practice requires the prescriber to confirm the accuracy of the patient’s weight for weight-based dosages as well as recording the weight on the medication chart.

One study (Hilmer) identified significant medication safety concerns and a risk of adverse drug events in patients that took weight-based medication and who had not been accurately weighed.

An unknown weight of a patient also may have Occupational Health and Safety implications for nursing staff.

Equipment used may also have a weight limit, especially those used for manual handling of a patient.

Identifying where risk will occur to staff and patients can only occur with an accurate weight and the use of equipment that can handle the weight being moved.

Patients who are at risk of compromised skin integrity (either under or overweight) are also at risk of pressure ulcers.

A baseline weight at admission is the start of monitoring skin integrity along with the review of a patient’s nutritional status.

Accurate morning daily weights were essential in heart failure disease care management.

To obtain an accurate patient daily, weight, patients should be weighed every morning, after their first void and before they eat breakfast. 

To learn more about accurate weight:

Evans, Alison. “Positive patient outcomes in acute care: does obtaining and recording accurate weight make a difference?.” Australian Journal of Advanced Nursing, The 29.3 (2012): 62.

Hilmer, S. N., et al. “Failure to weigh patients in hospital: a medication safety risk.” Internal medicine journal 37.9 (2007): 647-650.