If the person experiencing pain is the only one who can feel it, and there's no tool to precisely measure it, then self-reporting must be the best way to go, right? Not necessarily. There are a number of factors that affect the viability and reliability of such scales, including the ability to communicate, age and honesty.
In order to use self-reporting pain scales, patients must understand how they work and be able to respond appropriately, but this isn't always possible. Patients can have all kinds of communication barriers, from emotional and cognitive impairments to cultural or educational differences that make the scales difficult to grasp. Speech, or a lack thereof, can also present an obstacle: Patients might speak a different language or have a breathing tube, both of which hinder their ability to communicate verbally. Sadly, some people are simply too sick to effectively communicate their pain [source: Berry et al.].
Perhaps the greatest influence on a patient's capacity to communicate pain is age. Infants aren't able to read or understand doctors' questions, so pain scales aren't likely to be much help until they're 3 or 4 [source: Kishner et al.]. Likewise, elderly people — perhaps because of dementia, poor vision or diminished hearing — may have trouble understanding pain scales to a point that the results become unreliable.
Self-reporting pain scales can also become unreliable when patients have some incentive to mislead doctors. An obvious example is an addict who lies about his or her pain in order to get certain medications. While this certainly a problem, there are other far less nefarious reasons why people might misreport their pain. Take children, for example. They might give doctors a low pain score in order to avoid an injection or other uncomfortable procedure, even if they are truly hurting. Elderly folks might underreport pain too, perhaps to cover up new disabilities or simply to avoid being a bother. Either way, doctors may have to use other measures to double-check a patient's self-report. But how?