Niranjan Kathe

Assessment of Reliability and Validity of SF-12v2 among a Diabetic Population

OBJECTIVES To validate the Medical Outcomes Study Short Form version 2 (SF-12v2) in diabetic patients. METHODS Adults with self-reported diabetes from the Medical Expenditure Panel Survey (2011-2013) were identified. Reliability (internal consistency and test-retest) and validity (construct, concurrent, criterion, and predictive) of the SF-12v2 were assessed. The SF-12v2 consists of two normalized composite scores: the physical component summary score (PCS12) and the mental component summary score (MCS12). Confirmatory factor analysis was conducted to assess the instrument structure. Concurrent (convergent and discriminant) validity was assessed by a multitrait-multimethod matrix using the Patient Health Questionnaire, the Kessler Scale, and perceived health and mental health questions. The predictive validity was assessed by estimating future limitations. The concurrent validity was tested by comparing the MCS12, PCS12, and utility scores (six-dimensional health state short form) across comorbidity scores. RESULTS The final sample comprised 2214 diabetic patients with mean normalized (population mean 50; range 0-100) PCS12 and MCS12 scores of 40.81 (standard error 0.33) and 49.82 (standard error 0.26), respectively. The PCS12 and MCS12 scores showed good internal consistency (Cronbach α: PCS12 0.85; MCS12 0.83) and acceptable test-retest reliability (intraclass correlation coefficient: PCS12 0.72; MCS12 0.63) and produced acceptable goodness-of-fit indices (normed fit index 0.95; comparative fit index 0.95; root mean square error of approximation 0.11 [95% confidence interval 0.1017-0.1188]). The PCS12 and MCS12 were moderately correlated with perceived health and perceived mental health. The MCS12 was highly correlated with the Patient Health Questionnaire and the Kessler Scale. Both the PCS12 and the MCS12 could predict the future health limitations. The PCS12, MCS12, and utility scores demonstrated sensitivity to the presence of comorbidity scores. CONCLUSIONS The SF-12v2 is a valid generic instrument for measuring quality of life in diabetic patients.

Effectiveness and Safety of Magnesium Replacement in Critically Ill Patients Admitted to the Medical Intensive Care Unit in an Academic Medical Center: A Retrospective, Cohort Study

Background: “Rules of thumb” for the replacement of electrolytes, including magnesium, in critical care settings are used, despite minimal empirical validation of their ability to achieve a target serum concentration. This study’s purpose was to evaluate the effectiveness and safety surrounding magnesium replacement in medically, critically ill patients with mild-to-moderate hypomagnesemia. Methods: This was a single-center, retrospective, observational evaluation of episodes of intravenous magnesium replacement ordered for patients with mild-to-moderate hypomagnesemia (1.0-1.9 mEq/L) admitted to a medical intensive care unit from May 2014 to April 2016. The primary effectiveness outcome, achievement of target serum magnesium concentration (≥2 mEq/L) compared to expected achievement using a “rule of thumb” estimation that 1 g intravenous magnesium sulfate raises the magnesium concentration 0.15 mEq/L, was tested using 1-sample z test. Logistic regression analysis was conducted to assess the effect of infusion rate on target achievement. Results: Of 152 days on which magnesium replacements were provided for 72 patients, a follow-up serum magnesium concentration was checked within 24 hours in 89 (58.6%) episodes. Of these 89 episodes, serum magnesium concentration reached target in only 49 (59.8%) episodes compared to an expected 89 (100%; P < .0001). There was no significant association between infusion rate and achievement of the target serum magnesium concentration (odds ratio: 0.962, 95% confidence interval: 0.411-2.256). Conclusions: Medically, critically ill patients who received nonprotocolized magnesium replacement achieved the target serum magnesium concentration less frequently than the “rule of thumb” estimation predicted.

Reliability and validity of SF-12v2 among adults with self-reported cancer

Background: The SF‐12v2 has been validated in general population and other conditions but the evidence is limited in Americans with cancer. Objective: To assess reliability and validity of SF‐12v2 among adults with self‐reported cancer using the Medical Expenditure Panel Survey (MEPS). Methods: Self‐reported cancer participants (SCPs) were identified from 2003 MEPS. SF‐12v2 was administered as part of self‐administered questionnaires. Physical (PCS12) and mental (MCS12) component scores of SF‐12v2 were evaluated for reliability (internal consistency, test‐retest) and validity (convergent, discriminant, predictive, concurrent). Results: 420 SCPs were identified with average age of 59.3 years (SE=0.9). 10.7% had multiple cancers (>1) and 52% had at least one other chronic condition (OCC). Average PCS12 and MCS12 were 45.09 (SE=0.5) and 50.75 (SE=0.5). PCS12 and MCS12 demonstrated high internal consistency (&agr;PCS12=0.89; &agr;MCS12=0.88), acceptable test‐retest reliability (ICCPCS12=0.82; ICCMCS12=0.73), strongly correlated with most of the expected EQ‐5D domains (r=0.51–0.71), and demonstrated strong convergent validity on perceived health (r=0.61) and perceived mental health (r=0.52). PCS12 and MCS12 were able to discriminate between groups with and without physical/cognitive limitations. Only PCS12 was negatively correlated with number of OCCs. Conclusion: The SF‐12v2 is a reliable and valid instrument to quantify health‐related quality of life among adults with self‐reported cancer.

Consumer willingness to pay for pharmacy services: An updated review of the literature

Background: Quantifying the value of pharmacy services is imperative for the profession as it works to establish an expanded role within evolving health care systems. The literature documents the work that many have contributed toward meeting this goal. To date, however, the preponderance of evidence evaluates the value of pharmacist services to third‐party payers; few published studies address the value that consumers place on these services. Objectives: In 1999, a review of studies that used the contingent valuation method to value pharmacy services was published. The objective of this manuscript is to provide an update of that review. Methods: Relevant studies published in the English language were identified searching MEDLINE, ECONLIT and International Pharmaceutical Abstracts databases from January 1999 to November 2017. Only studies that specifically elicited willingness to pay for a community pharmacist provided service from actual or potential consumers were included. Results: Thirty‐one studies using the contingent valuation method to value pharmacy services were identified using the search strategy outlined. These studies included surveys in different demographic and geographic populations and valuing various pharmacy services. Conclusions: Improving the quality of studies using contingent valuation to value pharmacy services will aid the profession in marketing pharmacy services to consumers, and may assist practitioners who wish to implement various pharmacy services in their practice settings. A limited number of studies have been conducted, but the quality of contingent valuation studies valuing pharmacist services is improving. Understanding the pharmacy services that consumers value, and understanding the level of their monetary willingness to pay for those services will be crucial as the profession continues to work toward establishing a sustainable and economically viable role within the evolving health care systems.

Deficiencies of Magnesium Replacement in the Critically Ill

We are thankful for your additional insights into the clinical evaluation and management of patients with mild-to-moderate hypomagnesemia. We agree that the literature for magnesium replacement that was established in patients experiencing an acute myocardial infarction is essential to our understanding of the expected effects from replacement strategies. Patients in these studies received larger doses than patients in our study, had higher serum magnesium concentration targets than our medically, critically ill patients, and likely experienced greater renal excretion of magnesium because of the more pronounced concentration gradient that was established compared to our patients. For these reasons, the observed serum magnesium increases of 0.07 to 0.11 mEq/L per 1 g of intravenous magnesium sulfate are understandably lower than the increase we expected in our patients (0.15 mEq/L per 1 g of intravenous magnesium sulfate). Many variables were considered for collection beyond those that were reported in our study, including variables the authors suggested that may have affected acute changes in serum magnesium concentrations. While the duration of magnesium infusions was not provided directly, the infusion rates were described as being 1 and >1 g per hour because historically these break points have been considered to affect renal excretion of magnesium. At our institution, magnesium replacement was accomplished using premade intravenous piggyback infusions that had either 2 or 4 g magnesium sulfate in 50 mL of dextrose 5% in water. We did not believe the type of intravenous access (ie, central or peripheral) was of significant importance and, as such, did not evaluate this variable. We do agree that chronic use of proton pump inhibitor therapy may affect serum magnesium concentrations; however, we appreciate that these concerns are predominately seen with chronic, long-term use of proton pump inhibitor therapy and more so in patients who are not receiving intravenous magnesium replacement. Additionally, although no patients in this study receive parenteral nutrition, we do agree that the nutrition that was provided or withheld could have affected serum magnesium concentrations and should have been considered more heavily. Finally, the authors’ questions regarding serum creatinine values and chronic kidney disease definitions are well-founded. We defined chronic kidney disease as any patient with stage 3 or greater disease; however, patients experiencing an episode of acute kidney injury were able to be included, which may have affected our results. We appreciate the comments and questions from the authors and look forward to future research in this area.