Of the 162 participants, 151 participants had primary complaints of knee OA (53% [n = 80] self-reported OA in other joints), and 11 had hip OA (82% [n = 9] self-reported OA in other joints). Kellgren-Lawrence scores were distributed as follows: 1 (1.23%), 2 (21.60%), 3 (41.36%), and 4 (35.80%). Additional descriptive information is provided in Table . Furthermore, Table includes the overall number of reported medications and supplements. Five participants reported not taking any medications or supplements. Three of the five participants were managing their joint symptoms with intra-articular injections only. Another participant that reported no medications or supplements stated that she was avoiding medication use because of an adverse event with an intra-articular injection. The final participant reported no medication or supplement use but did not provide a reason for doing so. These 5 participants were excluded from the remainder of the analyses.
Study sample characteristics (n = 162)
Pharmacological and supplemental use among osteoarthritis knee and hip patients
The type and source of pharmacological and supplement use information is reported in Table . The most common class of intervention was NSAIDs (particularly naproxen [29.6%] and ibuprofen [24.1%]) followed by other analgesics (i.e., prescription analgesics), acetaminophen, and nutritional supplements. Half of the participants reported using prescription medications only, while approximately a quarter of the participants used OTC medications and supplements only. Almost 20% of the participants used both prescription and OTC medications and supplements. Most patients (55.6%) reported only professionally-guided recommendations, 24.1% indicated only self-guided recommendations, and 17.3% reported professionally and self-guided recommendations for their medication and supplement use. Results of the logistic regression used to evaluate predictors (i.e., ethnicity, sex, obesity, age, reporting multiple OA joints, and education) of a participant only using self-guided recommendations compared to only using professionally-guided recommendations was not significant (p = 0.149).
Also reported in Table is the pattern of medication use information. Less than half of the participants were always able to recall their medication dose, while the balance was either unable or partially able to do so. Twenty-nine percent of the participants reported never or only sometimes using their medication and/or supplement as directed, while the balance reported they always took their medication and/or supplement as directed. Results of the logistic regression used to evaluate predictors (i.e., ethnicity, sex, obesity, age, reporting multiple OA joints, and education) of a participant not always using their medication as directed was not significant (p = 0.139). Approximately half of the participants reported taking their medication and/or supplement consistently for 2 weeks whereas the others did not.
Thirty-seven (23%) participants were same day dual-medication and/or supplement users while 15 (9%) participants were taking the combinations at the same time. Dual-medication and/or supplement use pattern information is represented in Table . The majority of participants used multiple classes of medications at the same time. Eighty-six percent of dual-use participants reported using prescription medications only or both prescription and OTC medications at the same time.
Day and time patterns of multiple-medication use among osteoarthritis knee and hip patients
Results of the logistic regression to evaluate predictors of an individual being a same day dual-medication user were statistically significant. The Homer-Lemeshow goodness-of-fit test showed a good model fit with the data (p = 0.912). The overall accuracy of the model was 75.8% with a sensitivity of 44.4% and specificity of 77.7%. Participants reporting OA at multiple joints were more likely to be same day dual-medication users (odds ratio [95% confidence interval; CI] = 2.48 [1.03 to 5.96]) after controlling for covariates (i.e., ethnicity, sex, obesity, age, and education). In contrast, participants with less than a high school education were 3.82 times less likely to be same day dual-medication users (odds ratio [95% CI] = 0.26 [0.08 to 0.83]) than participants with a high school education or greater.
The source of recommendation of same time dual-medication and/or supplement use is reported in Table . Two participants reported 2 distinct patterns of dual use, resulting in fifteen participants reporting 17 dual-use combinations. Of these 17 dual-use combinations, 11 (65%) were professionally-guided based recommendations (physician-physician), 5 (29%) were professional and self-guided-based recommendations (physician-self), and 1 (6%) was a self-guided-based recommendation (self-self). Common combinations included NSAIDs plus analgesics (e.g., acetaminophen, tramadol; 9 out of 17) and medication plus supplement (e.g., calcium glucosamine; 5 out of 17).
Source of recommendation of dual-medication or nutritional supplement use among osteoarthritis knee and hip patients
Table describes several additional behaviors that participants reported to manage joint symptoms. Twenty-nine (18.5%) participants reported their medication as ineffective, required a stronger medication, or used illegal drugs to manage their symptoms. Alternatively, 15 (9.6%) participants sought an alternative method to achieve symptom relief (i.e., emergency room for symptom management, used other person's prescription medication, or used medication prescribed for an alternative ailment). Overall, 28% of participants reported their intervention as ineffective, sought an alternative method to achieve symptom relief, or were prescribed a stronger medication. Results of the logistic regression used to evaluate predictors (i.e., ethnicity, sex, obesity, age, reporting multiple OA joints, and education) of a participant reporting their medication as ineffective or requiring a stronger medication was not significant (p = 0.087). Conversely, Fisher's Exact Test revealed that participants who reported not always taking their medication consistently for 2 weeks were more likely to report their medication as ineffective (24.6% of participants) compared to participants always taking their medication consistently for 2 weeks (10.2% of participants; odds ratio [95% CI] = 2.87 [1.19 to 6.92], p = 0.010). No association was found between participants reporting medication as ineffective or requiring stronger medication and not always using medication as directed (p = 0.153). Thirteen participants reported other reasons for discontinuing their medication (e.g., no longer needed the medication, physician concerns regarding potential risks, patient fear of addiction, insurance refused to cover medication).
Additional behaviors among medication and supplement users (n = 157)