Seven hundred and twelve patients who received 10 mg of morphine sulfate or 20 mg of pentazocine or both for acute postoperative pain were studied for possible correlations between pain relief and patient characteristics. Age proved to be highly correlated with pain relief reports, in that the older age group reported more pain relief. These data are consistent with the results of earlier studies of experimental pain, as well as with the results of studies of the response of patients to placebos. We believe that it is more important to adjust dosage of a narcotic analgesic in relation to a patient's age than in relation to height, weight, or other patient characteristics.
J. Weldon Bellville, William H. Forrest, Elliott Miller, Byron W. Brown. Influence of Age on Pain Relief From AnalgesicsA Study of Postoperative Patients. JAMA. 1971;217(13):1835–1841. doi:10.1001/jama.1971.03190130039008