Comparison of three salivary flow rate assessment methods in an elderly population

Measuring salivary flow rates among the frail elderly is a challenge. The currently used spit collection method requires levels of time and cooperation that often may exclude the frail elderly who are at high risk for salivary compromise. A measurement method that is not only valid and reliable, but also feasible and acceptable is needed for use in population studies of compromised adults. This study compared two salivary flow rate assessment methods using a suction machine against the currently accepted spit collection method in an elderly population aged 75 and older. Three methods of flow rate (g/min) assessment were compared at three time periods among 16 elders (mean age 86.6 years). Flow rates using the 2-min open suction method compared well with the 10-min spit method (r=0.778) but the 2-min closed suction method did not (r=0.158). Reliability evaluation of the open suction method and the spit method was assessed using a test/retest with a 1-week interval. Both methods demonstrated good comparable reliability (spit method r=0.566, P=0.01); open suction method, (r= 0.861, P<0.01). Based on a short survey questionnaire about the three methods, 11 of the 16 elderly subjects preferred the use of the suction machine to the spit method. These results indicate that the 2-min open suction method technique is a valid and reliable means of measuring salivary flow. The lower level of patient cooperation needed, the shorter time period required, and this preliminary report of its acceptability support the use of this method in future population studies of frail elders.