Comparison of the cost-effectiveness of sequential treatment with abaloparatide in US men and women at very high risk of fractures.

BACKGROUND: Osteoporotic-related fractures represent an increasing burden to patients, health care systems and society. AIMS: This study estimated cost-effectiveness of sequential treatment with abaloparatide (ABL) followed by alendronate (ALN) compared to relevant alternative strategies in US men and women aged 50 to 80 years at very high fracture risk (bone mineral density T-score ≤ - 2.5 and a recent fracture). METHODS: A lifetime Markov-based microsimulation model was used to estimate healthcare costs and quality-adjusted life years (QALYs). Comparators were sequential treatment with unbranded teriparatide (TPTD)/ALN, generic ALN monotherapy, and no treatment. Analyses were conducted based on initial fracture site (hip, vertebral, or any fracture) and treatment efficacy data (derived from clinical trials or a recent network meta-analysis). RESULTS: From all analyses completed, sequential ABL/ALN demonstrated more QALYs for lower healthcare costs versus unbranded TPTD/ALN. No treatment was dominated (higher costs for less QALYs) versus ALN monotherapy. Sequential ABL/ALN resulted in favorable cost-effectiveness (at US threshold of $150,000/QALY) versus generic ALN monotherapy in men aged ≥ 50 years with any fracture type, women aged ≥ 65 years with any fracture type, and women aged ≥ 55 years having a hip or vertebral fracture. DISCUSSION: Similar cost-effectiveness of sequential ABL/ALN versus unbranded TPTD/ALN, ALN monotherapy, and no treatment was observed in both US men and women at very high fracture risk, with a moderate improvement in cost-effectiveness in men versus women and in patients with a hip or vertebral fracture. CONCLUSIONS: Sequential therapy with ABL/ALN was cost-effective in US men and women at very high risk of fractures.

Cost-Effectiveness of Sequential Abaloparatide/Alendronate in Men at High Risk of Fractures in the United States.

BACKGROUND AND OBJECTIVES: Abaloparatide (ABL) significantly increases bone mineral density in men with osteoporosis similar to what was reported in postmenopausal women with osteoporosis. The cost effectiveness of sequential treatment with ABL followed by alendronate (ALN) in men at high fracture risk was compared to relevant alternative treatments. METHODS: A Markov-based microsimulation model based on a lifetime US healthcare decision maker perspective was developed to evaluate the cost (expressed in US$2021) per quality-adjusted life-years (QALYs) gained of sequential ABL/ALN. Comparators were sequential treatment unbranded teriparatide (TPTD)/ALN, generic ALN monotherapy, and no treatment. Discount rates of 3% were used. Consistent with practice guidelines, patients received 18 months of ABL or TPTD followed by ALN for 5 years, or 5 years of ALN monotherapy. Analyses were conducted in high-risk men aged over 50 years defined as having a bone mineral density T-score ≤-2.5 and a recent fracture. Time-specific risk of subsequent fracture after a recent fracture, incremental costs up to 5 years following fractures, real-world medication adherence, and mostly US men-specific data were included in the model. One-way and probabilistic sensitivity analyses were conducted to assess the robustness of results. RESULTS: Over the full age range, sequential ABL/ALN led to more QALYs for lower costs than sequential unbranded TPTD/ALN, while no treatment was dominated (more QALYs, lower costs) by ALN monotherapy. The costs per QALY gained of sequential ABL/ALN were lower than the US threshold of US$150,000 versus generic ALN monotherapy. The probabilities that sequential ABL/ALN was cost effective compared to ALN monotherapy were estimated at 51% in men aged 50 years and between 88 and 90% in those aged ≥ 60 years. CONCLUSIONS: Sequential therapy using ABL/ALN may be cost effective compared with generic ALN monotherapy in US men aged ≥ 50 years at high fracture risk, especially in those aged ≥ 60 years. Unbranded TPTD/ALN and no treatment were dominated interventions (less QALY, more costs) compared with ABL/ALN or ALN monotherapy.

Real-World Management of Patients With Osteoporosis at Very High Risk of Fracture.

INTRODUCTION: Lack of consideration for risk-based assessments that inform osteoporosis treatment decisions may contribute to disease burden. In this study, we examined the prevalence of patients at very high risk of fracture and evaluated real-world treatment practices for these patients. METHODS: This retrospective observational cohort study used real-world data linked to commercial and Medicare medical claims from Symphony Health PatientSource. Patients 50 years and older with osteoporosis (determined by the presence of a diagnosis code) and at very high risk of fracture according to the American Association of Clinical Endocrinologists (AACE) and American College of Endocrinology (ACE) (AACE/ACE) 2020 guidelines between January 1, 2018, and December 31, 2018, were included. The number and proportion of patients treated with any osteoporosis medication were evaluated. RESULTS: Of the 10,739,286 patients with osteoporosis, 5,078,111 (47.3%) were identified as meeting the AACE criteria for very high risk of fracture and were selected for the analysis. Most (5,033,106 [99.1%]) had a high risk of falls and/or a history of falls resulting in injury. Among the 1,667,794 patients (32.8%) eligible for treatment, 280,777 (16.8%) received treatment. Of these, 63.6% received alendronate, an alternative therapy, and 21.2% received a risk-based guideline-recommended medicine (teriparatide, zoledronic acid, denosumab, abaloparatide, or romosozumab). A greater proportion of men were untreated, 161,978 (90.5) compared with 1,185,003 women (81.8). DISCUSSION: Most patients at very high risk of fracture remain untreated. Most of those treated do not receive the appropriate recommended treatments for patients at high risk. Risk-based treatment decisions may allow for more appropriate medication selection.

An Evaluation of Treatment Patterns for Osteoporosis and Outcomes After a Fragility Fracture in a Real-World Setting.

OBJECTIVES: Treatment initiation and persistence after a fragility fracture are critical to reduce the risk of subsequent fractures. The authors evaluated osteoporosis management and outcomes after index fracture. METHODS: This retrospective cohort study used real-world data for patients (≥50 years), including pharmacy claims linked to commercial and Medicare medical claims from Symphony Health Patient Source. Osteoporosis management was evaluated for at least 12 months after the first case-qualifying fracture during the identification period and continued until a second fracture or March 31, 2020 (depending on data availability). Secondary fracture incidence was evaluated overall and for subgroups at very high risk. RESULTS: Of 755,312 eligible patients, the proportion with a claim for bone mineral density testing at 12 months after index fracture was low [64,932 (8.6%)], and 75.3% of those tested were ≥65 years of age. Most patients (88.6%) remained untreated at any time after fracture. Among those treated, most (64.9%) were initially treated with bisphosphonates (oral, 93.7%; IV, 6.3%). Treatment duration and persistence were low for all treatments ranging from 6.5 months with 19.6% persistent for abaloparatide to 11.3 months with 45.0% persistent for denosumab. During follow-up, 13.6% of patients had a secondary fracture at any site, with higher incidence in subgroups considered to be at high risk for fracture than in the overall population. CONCLUSIONS: Low rates of osteoporosis testing and treatment initiation and high secondary fracture rates (particularly among patients at very high risk) highlight the need for better management of patients after a fracture. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Development and validation of a one year predictive model for secondary fractures in osteoporosis.

The number of osteoporosis-related fractures in the United States is no longer declining. Existing risk-based assessment tools focus on long-term risk. Payers and prescribers need additional tools to identify patients at risk for imminent fracture. We developed and validated a predictive model for secondary osteoporosis fractures in the year following an index fracture using administrative medical and pharmacy claims from the Optum Research Database and Symphony Health, PatientSource. Patients ≥50 years with a case-qualifying fracture identified using a validated claims-based algorithm were included. Logistic regression models were created with binary outcome of a second fracture versus no second fracture within a year of index fracture, with the goal of predicting second fracture occurrence. In the Optum Research Database, 197,104 patients were identified with a case-qualifying fracture (43% commercial, 57% Medicare Advantage). Using Symphony data, 1,852,818 met the inclusion/exclusion criteria. Average patient age was 70.09 (SD = 11.09) and 71.28 (SD = 14.24) years in the Optum Research Database and Symphony data, respectively. With the exception of history of falls (41.26% vs 18.74%) and opioid use (62.80% vs 46.78%), which were both higher in the Optum Research Database, the two populations were mostly comparable. A history of falls and steroid use, which were previously associated with increased fracture risk, continue to play an important role in secondary fractures. Conditions associated with bone health (liver disease), or those requiring medications that impact bone health (respiratory disease), and cardiovascular disease and stroke-which may share etiology or risk factors with osteoporosis fractures-were also predictors of imminent fractures. The model highlights the importance of assessment of patient characteristics beyond bone density, including patient comorbidities and concomitant medications associated with increased fall and fracture risk, in alignment with recently issued clinical guidelines for osteoporosis treatment.

Gender Disparities in Osteoporosis Screening and Management Among Older Adults.

INTRODUCTION: One in two women and one in four men experience an osteoporosis-related fracture in their lifetime. Related morbidity and mortality rates are higher in men versus women. Current guidelines are inconsistent in the screening recommendations for osteoporosis in men. Examination of gender disparities in the management of osteoporosis-related fractures among Medicare enrollees is currently lacking. METHODS: In this retrospective cohort study using 5% National Medicare claims data from January 1, 2012 through December 31, 2016, eligible patients who were at least 65 years of age on the date of a new fracture episode were classified into two mutually exclusive cohorts on the basis of whether they received testing and/or treatment for osteoporosis in the 6-month period after the new fracture episode. The cohorts were defined on the basis of the National Committee for Quality Assurance (NCQA) quality measure "osteoporosis management in women who had a fracture." Patients were followed to identify the occurrence of subsequent fracture, all-cause mortality, and a composite outcome-defined as the first occurrence of either subsequent fracture or mortality. Logistic regression models were carried out to identify predictors of testing and/or treatment and time-varying survival analysis to identify the relationship between the presence of testing and/or treatment and patient outcomes. RESULTS: Of the 35,774 eligible patients, only 10.2% (12.1% women and 5.7% men) received osteoporosis testing and/or treatment within 6 months after a fracture. The interaction between gender and fragility fracture was significant (P < 0.0001). Fragility fracture had greater adjusted odds of testing and/or treatment among men (adjusted odds ratio [AOR] 3.47; 95% CI 2.94-4.10) than women (AOR 1.65; 95% CI 1.53-1.79). Of patients who were eligible for the outcome assessment, 27.5% experienced a subsequent fracture, 23.2% died, and 44.3% experienced a composite outcome during follow-up. Patients who received testing and/or treatment had a significantly lower hazard of all-cause mortality (hazard ratio [HR] 0.57; 95% CI 0.50-0.65; P < 0.0001) and the composite outcome (HR 0.42; 95% CI 0.39-0.45; P < 0.0001), but no difference in the risk of subsequent fracture (HR 1.02; 95% CI 0.94-1.11; P = 0.6083). Men were found to have a significantly lower hazard of subsequent fracture (HR 0.69; 95% CI 0.64-0.73; P < 0.0001), all-cause mortality (HR 0.67; 95% CI 0.61-0.72; P < 0.0001), and the composite outcome (HR 0.69; 95% CI 0.65-0.73; P < 0.0001). CONCLUSION: Testing and/or treatment for osteoporosis among older adults with a fracture is poor in the Medicare fee-for-service population overall and worse for men compared to women. Receiving appropriate testing and/or treatment was associated with reduced mortality and the risk of composite outcome. Improving osteoporosis testing and/or treatment and reducing health disparities are essential for managing the clinical and economic burden of osteoporosis in the USA.

Economic Burden of Osteoporosis-Related Fractures in the US Medicare Population.

BACKGROUND: Osteoporosis-related fractures are an important public health burden. OBJECTIVE: To examine health care costs in Medicare patients with an osteoporosis-related fracture. METHODS: Medicare fee-for-service members with an osteoporosis-related fracture between January 1, 2010, to September 30, 2014 were included. A nonfracture comparator group was selected by propensity score matching. Generalized linear models using a gamma distribution were used to compare costs between fracture and nonfracture cohorts. RESULTS: A total of 885 676 Medicare beneficiaries had fracture(s) and met inclusion criteria. Average age was 80.5 (±8.4) years; 91% were White, and 94% female. Mean all-cause costs were greater in the fracture vs nonfracture cohort ($47 163.25 vs $16 034.61) overall and for men ($52 273.79 vs $17 352.68). The highest mean costs were for skilled nursing facility ($29 216), inpatient costs ($24 190.19), and hospice care ($20 996.83). The highest incremental costs versus the nonfracture cohort were for hip ($71 057.83 vs $16 807.74), spine ($37 543.87 vs $16 860.49), and radius/ulna ($24 505.27 vs $14 673.86). Total medical and pharmacy costs for patients who experienced a second fracture were higher compared with those who did not ($78 137.59 vs $44 467.47). Proportionally more patients in the fracture versus nonfracture cohort died (18% vs 9.3%), with higher death rates among men (20% vs 11%). CONCLUSION AND RELEVANCE: The current findings suggest a significant economic burden associated with fractures. Early identification and treatment of patients at high risk for fractures is of paramount importance for secondary prevention and reduced mortality.

Economic burden of osteoporotic fractures in US managed care enrollees.

OBJECTIVES: To examine healthcare resource utilization (HRU) and costs in a population of managed care enrollees who experienced an osteoporotic fracture. STUDY DESIGN: Retrospective cohort study using the Optum Research Database (January 2007 to May 2017). METHODS: All-cause and osteoporosis-related HRU and costs were analyzed in patients 50 years and older with a qualifying index fracture and continuous enrollment with medical and pharmacy benefits for 12 months preindex (baseline period). RESULTS: Of 1,841,263 patients with fractures during the identification period, 302,772 met eligibility criteria. Two-thirds (66.6%) were 65 years and older, 71.6% were women, and 41.2% were commercial (not Medicare Advantage) enrollees. The most common fracture sites were spine (21.9%), radius/ulna (19.5%), and hip (13.7%). Mean (SD) total all-cause healthcare cost was $34,855 ($56,094), with most paid by health plans ($31,863 [$55,025]) versus patients ($2992 [$2935]). Most healthcare costs were for medical ($31,766 [$54,943]) versus pharmacy ($3089 [$6799]) services. Approximately 75% of patients received rehabilitation services (mean [SD] cost = $18,025 [$41,318]). Diagnosis of index fracture during an inpatient stay versus an outpatient visit (cost ratio, 2.16; 95% CI, 2.13-2.19) and fractures at multiple sites (cost ratio, 1.23; 95% CI, 1.21-1.26) were the leading predictors of cost. Kaplan-Meier estimated cumulative second-fracture rates were 6.6% at 1 year, 12.3% at 2 years, 16.9% at 3 years, and 20.9% at 4 years after index fracture. CONCLUSIONS: These findings suggest a significant economic burden associated with fractures, including a high total all-cause cost of care. Early identification and treatment of patients at high risk of fractures are of paramount importance to reduce fracture risk and associated healthcare costs.

Cost-effectiveness Analysis of Sequential Treatment of Abaloparatide Followed by Alendronate Versus Teriparatide Followed by Alendronate in Postmenopausal Women With Osteoporosis in the United States.

BACKGROUND: The US Food and Drug Administration has recently approved abaloparatide (ABL) for treatment of women with postmenopausal osteoporosis (PMO) at high risk of fracture. With increasing health care spending and drug prices, it is important to quantify the value of newly available treatment options for PMO. OBJECTIVE: To determine cost-effectiveness of ABL compared with teriparatide (TPTD) for treatment of women with PMO in the United States. METHODS: A discrete-event simulation (DES) model was developed to assess cost-effectiveness of ABL from the US health care perspective. The model included three 18-month treatment strategies with either placebo (PBO), TPTD, or ABL, all followed by additional 5-year treatment with alendronate (ALN). High-risk patients were defined as women with PMO ⩾65 years old with a prior vertebral fracture. Baseline clinical event rates, risk reductions, and patient characteristics were based on the Abaloparatide Comparator Trial in Vertebral Endpoints (ACTIVE) trial. RESULTS: Over a 10-year period, the DES model yielded average total discounted per-patient costs of $10 212, $46 783, and $26 837 and quality-adjusted life-years (QALYs) of 6.742, 6.781, and 6.792 for PBO/ALN, TPTD/ALN, and ABL/ALN, respectively. Compared with TPTD/ALN, ABL/ALN accrued higher QALYs at lower cost and produced an incremental cost-effectiveness ratio (ICER) of $333 266/QALY relative to PBO/ALN. In high-risk women, ABL/ALN also had more QALYs and less cost over TPTD/ALN and yielded an ICER of $188 891/QALY relative to PBO/ALN. Conclusion and Relevance: ABL is a dominant treatment strategy over TPTD. In women with PMO at high risk of fracture, ABL is an alternative cost-effective treatment.

A vector system for efficient and economical switching of a ura4(+) module to three commonly used antibiotic marker cassettes in Schizosaccharomyces pombe.

We describe here the development of a set of plasmid vectors that allow simple, efficient and economical switching of a ura4(+) module in existing Schizosaccharomyces pombe strains to any of the three routinely used antibiotic marker cassettes, kanMX6, hphMX6 and natMX6. In principle, the applications of this system can also be extended to switching ura4(+) for additional MX6 module-based cassettes, such as bleMX6, as long as the antibiotic marker has been cloned into an ura4(+) module-switching vector. We illustrate the application of this set of vectors in exchange of the ura4(+) marker in existing strains with three antibiotic marker cassettes with high efficiency.

A cost analysis of the impact of a new intravenous antihypertensive in managing perioperative blood pressure during cardiac surgery.

OBJECTIVE: To examine the impact of intravenous antihypertensive selection on hospital health resource utilization using data from the Evaluation of CLevidipine In the Perioperative Treatment of Hypertension Assessing Safety Events (ECLIPSE) trials. METHODS: Analysis of ECLIPSE trial data comparing clevidipine to nitroglycerin, sodium nitroprusside, and nicardipine and unit costs based on the Premier Hospital database to assess surgery duration, time to extubation, and length of stay (LOS) with the associated cost. RESULTS: A total of 1414 patients from the ECLIPSE trials and the Premier hospital database were included for analysis. The duration of surgery and postoperative LOS were similar across groups. The time from chest closure to extubation was shorter in patients receiving clevidipine group compared with the pooled comparator group (median 7.0 vs 7.6 hours, P = 0.04). There was shorter intensive care unit (ICU) LOS in the clevidipine group versus the nitroglycerin group (median 27.2 vs 33.0 hours, P = 0.03). A trend toward reduced ICU LOS was also seen in the clevidipine compared with the pooled comparator group (median 32.3 vs 43.5 hours, P = 0.06). The costs for ICU LOS and time to extubation were lower with clevidipine than with the comparators, with median cost savings of $887 and $34, respectively, compared with the pooled comparator group, for a median cost savings of $921 per patient. CONCLUSIONS: Health resource utilization across therapeutic alternatives can be derived from an analysis of standard costs from hospital financial data to matched utilization metrics as part of a randomized controlled trial. In cardiac surgical patients, intravenous antihypertensive selection was associated with a shorter time to extubation in the ICU and a shorter ICU stay compared with pooled comparators, which in turn may decrease total costs.

Impact of perioperative blood pressure variability on health resource utilization after cardiac surgery: an analysis of the ECLIPSE trials.

OBJECTIVE: To examine the impact of blood pressure control on hospital health resource utilization using data from the ECLIPSE trials. DESIGN: Post-hoc analysis of data from 3 prospective, open-label, randomized clinical trials (ECLIPSE trials). SETTING: Sixty-one medical centers in the United States. PARTICIPANTS: Patients 18 years or older undergoing cardiac surgery. INTERVENTIONS: Clevidipine was compared with nitroglycerin, sodium nitroprusside, and nicardipine. MEASUREMENTS AND MAIN RESULTS: The ECLIPSE trials included 3 individual randomized open-label studies comparing clevidipine to nitroglycerin, sodium nitroprusside, and nicardipine. Blood pressure control was assessed as the integral of the cumulative area under the curve (AUC) outside specified systolic blood pressure ranges, such that lower AUC represents less variability. This analysis examined surgery duration, time to extubation, as well as intensive care unit (ICU) and hospital length of stay (LOS) in patients with AUC≤10 mmHg×min/h compared to patients with AUC>10 mmHg×min/h. One thousand four hundred ten patients were included for analysis; 736 patients (52%) had an AUC≤10 mmHg×min/h, and 674 (48%) had an AUC>10 mmHg×min/h. The duration of surgery and ICU LOS were similar between groups. Time to extubation and postoperative LOS were both significantly shorter (p = 0.05 and p<0.0001, respectively) in patients with AUC≤10. Multivariate analysis demonstrates AUC≤10 was significantly and independently associated with decreased time to extubation (hazard ratio 1.132, p = 0.0261) and postoperative LOS (hazard ratio 1.221, p = 0.0006). CONCLUSIONS: Based on data derived from the ECLIPSE studies, increased perioperative BP variability is associated with delayed time to extubation and increased postoperative LOS.

Improved perioperative blood pressure control leads to reduced hospital costs.

BACKGROUND: Perioperative hypertension affects 80% of cardiac surgery patients and is associated with an increased risk of complications. OBJECTIVE: To determine the relationship between perioperative blood pressure (BP) control and hospital costs for cardiac surgery in the United States (US) and estimate the potential cost reductions associated with effective therapies. METHODS: The analysis estimated hospitalization costs (2011 US dollars (USD)) for cardiac surgery when BP was controlled with intravenous (IV) antihypertensives. Patient characteristics, hospital length of stay, and clinical event rates during the initial hospitalization and post-discharge 30 days after study drug infusion were based on the ECLIPSE (Evaluation of CLevidipine In the Perioperative Treatment of Hypertension Assessing Safety Events) trials. These clinical trial data were combined with data from the Massachusetts Acute Hospital Case Mix Database 2007 - 2009 (MA Case Mix Database) to estimate total hospitalization costs. RESULTS: Effective perioperative BP control in patients requiring IV antihypertensives was associated with a 7% decrease in hospital costs compared with less effective BP control. Reductions in total hospital costs associated with clevidipine versus other IV antihypertensives averaged $394 per patient overall. Cost savings with clevidipine exceeded $500 per patient versus sodium nitroprusside and nitroglycerin, but only $22 compared to nicardipine. CONCLUSION: Improved perioperative BP control may reduce hospital costs. Given the low cost of IV antihypertensives, the total hospital cost reductions may offset any incremental cost increases associated with newer, more effective therapies.

Accounting for the relationship between per diem cost and LOS when estimating hospitalization costs.

BACKGROUND: Hospitalization costs in clinical trials are typically derived by multiplying the length of stay (LOS) by an average per-diem (PD) cost from external sources. This assumes that PD costs are independent of LOS. Resource utilization in early days of the stay is usually more intense, however, and thus, the PD cost for a short hospitalization may be higher than for longer stays. The shape of this relationship is unlikely to be linear, as PD costs would be expected to gradually plateau. This paper describes how to model the relationship between PD cost and LOS using flexible statistical modelling techniques. METHODS: An example based on a clinical study of clevidipine for the treatment of peri-operative hypertension during hospitalizations for cardiac surgery is used to illustrate how inferences about cost-savings associated with good blood pressure (BP) control during the stay can be affected by the approach used to derive hospitalization costs.Data on the cost and LOS of hospitalizations for coronary artery bypass grafting (CABG) from the Massachusetts Acute Hospital Case Mix Database (the MA Case Mix Database) were analyzed to link LOS to PD cost, factoring in complications that may have occurred during the hospitalization or post-discharge. The shape of the relationship between LOS and PD costs in the MA Case Mix was explored graphically in a regression framework. A series of statistical models including those based on simple logarithmic transformation of LOS to more flexible models using LOcally wEighted Scatterplot Smoothing (LOESS) techniques were considered. A final model was selected, using simplicity and parsimony as guiding principles in addition traditional fit statistics (like Akaike's Information Criterion, or AIC). This mapping was applied in ECLIPSE to predict an LOS-specific PD cost, and then a total cost of hospitalization. These were then compared for patients who had good vs. poor peri-operative blood-pressure control. RESULTS: The MA Case Mix dataset included data from over 10,000 patients. Visual inspection of PD vs. LOS revealed a non-linear relationship. A logarithmic model and a series of LOESS and piecewise-linear models with varying connection points were tested. The logarithmic model was ultimately favoured for its fit and simplicity. Using this mapping in the ECLIPSE trials, we found that good peri-operative BP control was associated with a cost savings of $5,366 when costs were derived using the mapping, compared with savings of $7,666 obtained using the traditional approach of calculating the cost. CONCLUSIONS: PD costs vary systematically with LOS, with short stays being associated with high PD costs that drop gradually and level off. The shape of the relationship may differ in other settings. It is important to assess this and model the observed pattern, as this may have an impact on conclusions based on derived hospitalization costs.

Assessment of surface water quality using multivariate statistical techniques in red soil hilly region: a case study of Xiangjiang watershed, China.

In the study, multivariate statistical methods including factor, principal component and cluster analysis were applied to analyze surface water quality data sets obtained from Xiangjiang watershed, and generated during 7 years (1994-2000) monitoring of 12 parameters at 34 different profiles. Hierarchical cluster analysis grouped 34 sampling sites into three clusters, including relatively less polluted (LP), medium polluted (MP) and highly polluted (HP) sites, and based on the similarity of water quality characteristics, the watershed was divided into three zones. Factor analysis/principal component analysis, applied to analyze the data sets of the three different groups obtained from cluster analysis, resulted in four latent factors accounting for 71.62%, 71.77% and 72.01% of the total variance in water quality data sets of LP, MP and HP areas, respectively. The PCs obtained from factor analysis indicate that the parameters for water quality variations are mainly related to dissolve heavy metals. Thus, these methods are believed to be valuable to help water resources managers understand complex nature of water quality issues and determine the priorities to improve water quality.