Average Maintenance Cost Research Articles

A new statin, rosuvastatin, produces significant improvements in serum lipids and lipid ratios in patients with hypercholesterolaemia

Background: Previous health economic studies have demonstrated the cost-effectiveness of simvastatin in the treatment of coronary heart disease (CHD) based on clinical results of the Scandinavian Simvastatin Survival Study. A prior analysis evaluated the “cost of getting to goal,” but ignored all costs after titration. However, when evaluating the cost-effectiveness of long-term therapies, it is important to consider the maintenance costs as well.Objective: The purpose of this study was to evaluate the maintenance costs of treatment with simvastatin versus that of treatment with another more recently available statin, atorvastatin, in a European context.Methods: We assessed the long-term maintenance cost of simvastatin versus atorvastatin in terms of the cost of reducing low-density lipoprotein cholesterol (LDL-C) levels to the recommended goals based on a previously published clinical trial in patients with CHD. The analysis focused on the patients in the original clinical trial who were randomized to treatment with simvastatin or atorvastatin. Patients began therapy with 10 mg of simvastatin or atorvastatin; the dose of study drug was titrated every 12 weeks up to 40 mg simvastatin or 80 mg atorvastatin, with the addition of up to 8 g/d of cholestyramine until a modified European Atherosclerosis Society LDL-C goal (≤2.84 mmol/L) was reached. As there was no significant difference between the 2 groups in resource utilization for adverse events, only drug costs were included. The calculated average annual maintenance cost was based on the distribution of the final daily dosing regimens and the public drug prices for each regimen. Individual country analyses were conducted using each local currency.Results: There was no significant difference between groups in the percentage of patients reaching their LDL-C goal over the study period (80% for simvastatin-treated patients vs 89% for atorvastatin-treated patients, P = 0.135). However, the cost of maintaining a similar percentage of patients at their appropriate LDL-C levels was significantly lower in the simvastatin group compared with the atorvastatin group in 13 of the 17 countries assessed. In the remaining 4 countries, there was a cost advantage for simvastatin, but it did not reach statistical significance.Conclusions: Across Europe there was a significant reduction in the cost of maintaining patients at their appropriate LDL-C levels with simvastatin versus atorvastatin. The results of this analysis, along with the proven clinical benefits of simvastatin, support the use of this drug as the treatment of choice in the secondary prevention of CHD.

Cost-minimization analysis of simvastatin versus atorvastatin for maintenance therapy in patients with coronary or peripheral vascular disease

Background: Previous health economic studies have demonstrated the cost-effectiveness of simvastatin in the treatment of coronary heart disease (CHD) based on clinical results of the Scandinavian Simvastatin Survival Study. A prior analysis evaluated the “cost of getting to goal,” but ignored all costs after titration. However, when evaluating the cost-effectiveness of long-term therapies, it is important to consider the maintenance costs as well. Objective: The purpose of this study was to evaluate the maintenance costs of treatment with simvastatin versus that of treatment with another more recently available statin, atorvastatin, in a European context. Methods: We assessed the long-term maintenance cost of simvastatin versus atorvastatin in terms of the cost of reducing low-density lipoprotein cholesterol (LDL-C) levels to the recommended goals based on a previously published clinical trial in patients with CHD. The analysis focused on the patients in the original clinical trial who were randomized to treatment with simvastatin or atorvastatin. Patients began therapy with 10 mg of simvastatin or atorvastatin; the dose of study drug was titrated every 12 weeks up to 40 mg simvastatin or 80 mg atorvastatin, with the addition of up to 8 g/d of cholestyramine until a modified European Atherosclerosis Society LDL-C goal (≤2.84 mmol/L) was reached. As there was no significant difference between the 2 groups in resource utilization for adverse events, only drug costs were included. The calculated average annual maintenance cost was based on the distribution of the final daily dosing regimens and the public drug prices for each regimen. Individual country analyses were conducted using each local currency. Results: There was no significant difference between groups in the percentage of patients reaching their LDL-C goal over the study period (80% for simvastatin-treated patients vs 89% for atorvastatin-treated patients, P = 0.135). However, the cost of maintaining a similar percentage of patients at their appropriate LDL-C levels was significantly lower in the simvastatin group compared with the atorvastatin group in 13 of the 17 countries assessed. In the remaining 4 countries, there was a cost advantage for simvastatin, but it did not reach statistical significance. Conclusions: Across Europe there was a significant reduction in the cost of maintaining patients at their appropriate LDL-C levels with simvastatin versus atorvastatin. The results of this analysis, along with the proven clinical benefits of simvastatin, support the use of this drug as the treatment of choice in the secondary prevention of CHD.

3421 Cost analysis of gastrointestinal endoscopes: does age and usage affect the maintenance cost?

Aim To assess the equipment costs involved in providing an endoscopy service at a district general hospital. Method Data relating to the purchase price, the number and cost of maintenances and usage over the life of nineteen endoscopes (gastroscopes 12, colonoscopes 7) was collected from medical electronics records. The data was analysed using SPSS 7.5 to determine whether any causal relationships existed. Results The total number of endoscopies carried out by the fibreoptic endoscopes over a fifteen-year period amounted to 23,899 (15,534 [65%] using gastroscopes and 8,365 [35%] using colonoscopes).There were 162 maintenance episodes, an average of 8.5 per endoscope and just over 1 per endoscope/year (range 0.1-0.9). Of the tatal episodes, 92 (57%) were on gastroscopes and the rest 70 (43%) on colonoscopes. The average cost of each maintenance episode amounted to £715, (gastroscope £801, colonoscope £598). There was no correlation between the number of episodes and the total cost of maintenance per endoscope. The average maintenance cost per endoscope amounted to £4.85 (1.43-10.07), (gastroscope £4.85, colonoscope £4.66). When the purchase price was included the average cost per endoscopic procedure amounted to £22.03 (7.20-89.20) (gastroscope £18.81, colonoscope £27.57). This range is highly skewed because of the differential in prices of endoscopes purchased pre and during 1995. Four of the nineteen endoscopes (gastroscopes 2, colonoscopes 2) were purchased during 1995 and cost an average £19,625 compared to the other fifteen endoscopes purchased pre 1995 and cost an average £11,785. The average maintenance cost for the newer endoscopes was £6.42 per endoscope compared to £7.10 for the older endoscopes. The average cost per endoscopic procedure for the newer endoscopes was £51 compared to £19.52 for the older endoscopes. This difference in cost per endoscopic procedure can be attributed to the length of time over which the purchase price depreciates. Conclusion We have projected the average costs of procedure and maintenance of gastroscopes and colonoscopes. There was no significant correlation between the usage and maintenance costs over a fifteen-year period.Within this time period there is no evidence that endoscopes move to being beyond economic repair.

A comparative analysis between the multilayer perceptron “neural network” and multiple regression analysis for predicting construction plant maintenance costs

Notes that the real test of maintenance stratagem success (or failure in financial terms) can only be resolved when a comparison of machine maintenance costs can be made to some benchmark standard. Presents a comparative study between two models developed to predict the average hourly maintenance cost of tracked hydraulic excavators operating in the UK opencast mining industry. The models use the conventional statistical technique multiple regression, and artificial neural networks. Performance analysis using mean percentage error, mean absolute percentage error and percentage cost accuracy intervals was conducted. Results reveal that both models performed well, having low mean absolute percentage error values (less than 5 percent) indicating that predictor variables were reliable inputs for modelling average hourly maintenance cost. Overall, the neural network model performed slightly better as it was able to predict up to 95 percent of cost observations to within ≤q£5. Moreover, summary statistical analysis of residual values highlighted that predicted values using the neural network model are less subject to variance than the multiple regression model.

Evaluation of average maintenance cost for imperfect-repair model

The imperfect-repair model considers units which are either perfectly-repaired or minimally-repaired, with known, fixed probabilities. Minimal repair is defined, roughly, as returning the item to the population's average state at the failure time. The average cost of maintaining the unit under this model is studied by assuming fixed amounts of cost for perfect and minimal repairs when failed. The authors' measure of such maintenance cost is an average cost per unit-time over an infinite time span. To obtain this average cost, they use the expressions for average numbers of perfect and minimal repairs under this model. They prove the few theorems necessary to derive the formulae for the average cost per unit-time. The results are applied to some examples.

Design of an optimal BER monitoring scheme for preventive maintenance of an ATM network

In today's telecommunication networks it is well known that unexpected failures in the physical links may cause significant loss or interruption of services. It is desirable if the deterioration of links can be recognized early and maintenance is carried out before failure occurs. Asynchronous transfer mode (ATM) networks have recently received much attention and are considered to be the prime universal networks of the future. Unfortunately, there has been very little research in the areas of preventive maintenance and performance monitoring of the ATM network. In this paper we propose a preventive maintenance monitoring scheme for an ATM network where a performance index called the bit error rate (BER) index of each service of the ATM network is continuously monitored. The BER index of each path in the ATM network is assumed to be slowly deteriorating and is modelled as a Brownian motion process with positive drift. If any of the BER indices exceeds its action limit or threshold, a repair process is initiated. The optimal action limit is derived by minimizing the modified long-run average maintenance cost. We found that the optimal action limit depends strongly on the multiservice characteristics of the ATM network and on the network topology, which relates to the virtual path (VP) bandwidth management and routing protocol used. To obtain the optimal action limit, an optimization model for VP bandwidth management is set up and the multidimensional Erlang loss model is used to determine the path selecting probabilities. Some numerical examples are given to illustrate the proposed model and the optimization results. © 1998 John Wiley & Sons, Ltd.

Maintenance of light-standards—a case-study

This paper discusses several strategies for the maintenance of light standards, where each light standard consists of n independent and identical lamps screwed on a chandelier. The lamps are subject to stochastic failures, and must be correctively replaced if the number of failed lamps reaches a prespecified number m; a norm that is set by the local management to guarantee a minimumluminance. As lamps have an increasing failure rate, and there is a fixed cost of hoisting the chandelier, we propose various variants of the m-failure group replacement rule which have in particular an age-criterion to indicate which of the non-failed lamps must be preventively replaced at the time that the chandelier is lowered for a corrective lamp replacement; we show how the optimalthreshold age can be determined. It appears that this modification reduces the long run average maintenance cost of the Europe Combined Terminals with approximately 8.3%.

Maintenance of light-standards—a case-study

This paper discusses several strategies for the maintenance of light-standards, where each light-standard consists of n independent and identical lamps screwed on a lamp assembly. The lamps are subject to stochastic failures, and must be correctly replaced if the number of failed lamps reaches a prespecified number m, a norm that is set by the local management to guarantee a minimum luminance. As lamps have an increasing hazard rate and there is a fixed cost of hoisting the assembly, we propose various variants of the m-failure group replacement rule which have in particular an age-criterion to indicate which of the non-failed lamps must be preventively replaced at the time that the assembly is lowered for a corrective lamp replacement. We show how the optimal threshold age can be determined. It appears that this modification reduces the long run average maintenance cost of the Europe Combined Terminals by approximately 8.3%.

Development of a Knowledge-Based Formula to Prioritize Pavement Rehabilitation Projects

The development of a formula to prioritize pavement rehabilitation projects based on experts’ opinion is presented. This formula is used for the preparation of the Arizona Department of Transportation (ADOT) 5 yr pavement preservation program. The knowledge to determine the prioritization formula and treatment assignment criteria was captured from a group of experts using a survey design based on the rational factorial methodology. The survey questionnaire provided a set of pavement sections with different characteristics and asked the experts to indicate which sections should receive a rehabilitation treatment, what type of treatment they would recommend for each section, and which priority should be assigned to the resulting preservation project. Eight pavement characteristics (functional classification, geographical region, structural number, traffic, pavement rideability, cracking, rutting, and average maintenance cost for the past 3 yr) were identified as influence variables. A fractional factorial experiment design with four blocks was selected for the study. A questionnaire with a different set of pavement sections was prepared for each experimental block. The questionnaires were sent to pavement experts from ADOT headquarters and maintenance districts. The responses were analyzed, using linear regression analysis, to select the best models for the priority and treatment selection equations. The study showed that the rational factorial methodology is a powerful tool for capturing and quantifying expert opinions. The average opinion of the experts surveyed indicated that rutting, functional classification, roughness, cracking, traffic, and maintenance cost significantly influence the priority assigned to a preservation project. The treatment assignment model was less reliable; a larger panel of experts would be required to obtain a reliable model.

Optimum condition-based maintenance policies for deteriorating systems with partial information

Systems are considered which deteriorate as time goes on and whose conditions can be observed. The optimum maintenance policy with respect to cost is determined, based on a continuous deterioration process, by formulating the decision process as a discrete Markov decision problem. Examples from the field of civil engineering are given. The relation between the type of deterioration and condition-based optimum inspection intervals, optimum repair level, minimum average maintenance costs and mean time to repair is shown, using some numerical results.

Compressed Natural Gas and Liquefied Petroleum Gas as Alternative Fuels

This research by the Nebraska Department of Roads evaluated the use of liquefied petroleum gas (LPG) and compressed natural gas (NG) by 25 LPG-bifuel and 14 NG-bifuel vehicles operated by 33 transit systems throughout Nebraska. A set of performance measures such as average fuel efficiency in kilometers per liter, average fuel cost per kilometer, average oil consumption, and average operation and maintenance cost for alternatively fueled vehicles were calculated and compared with similar performance measures of gasoline powered vehicles. The study results showed that the average fuel efficiency of gasoline is greater than those of LPG and NG, and the average fuel costs for LPG and NG are smaller than those for gasoline for most of the vehicles studied.

De Finetti-type Representations for Life Distributions

Abstract Beginning with a finite population of units and the judgment of exchangeability for units with respect to lifetime, we argue that measures of similarity lead to the appropriate probabilistic models for aging. This in turn implies that Schur-concavity of the joint probability function (or, more generally, the joint survival distribution) provides the correct probabilistic description of aging. Following this argument and using the principle of indifference, we argue that the appropriate probability models for life distributions conditional on average life are in a family of distributions that we call the generalized gamma distributions. If, on the other hand, we are interested in probabilistic models for aging conditional on average lifetime maintenance cost, it follows from our development that generalized Weibull distributions are appropriate.

De Finetti-type Representations for Life Distributions

Abstract Beginning with a finite population of units and the judgment of exchangeability for units with respect to lifetime, we argue that measures of similarity lead to the appropriate probabilistic models for aging. This in turn implies that Schur-concavity of the joint probability function (or, more generally, the joint survival distribution) provides the correct probabilistic description of aging. Following this argument and using the principle of indifference, we argue that the appropriate probability models for life distributions conditional on average life are in a family of distributions that we call the generalized gamma distributions. If, on the other hand, we are interested in probabilistic models for aging conditional on average lifetime maintenance cost, it follows from our development that generalized Weibull distributions are appropriate.

Reduced Coated-Tubing Failures Cut Costs at Dickinson Heath Sand Unit

Summary In the Dickinson Heath Sand Unit waterflood, corrosion-related failures ofcoated injection tubing began accelerating in 1979 with the increased waterproduction attributed to waterflood response. The trend peaked in 1984 when$164,000 was spent pulling failed tubing (34 workovers). Starting in 1983, theselection of coatings, coating-application-process quality control, andhandling/installation procedures were examined, modified, and refined. Thesechanges and improvements resulted in fewer pulling jobs and less money spent onassociated workovers during 1988. Introduction The Dickinson Heath Sand Unit is near Dickinson, ND, in the southern sectionof the Williston basin. Production is from the Mississippian Heath formation at8,000 ft [2438 m], and bottomhole temperature is about 200F [93C]. Crude isprimarily asphaltic, with a specific gravity of 0.855 g/cm3, and the formationwater was saturated brine before waterflooding (Table 1). The field wasunitized for secondary recovery in 1973. At that time, the produced watervolume was insufficient to sustain the waterflood, so Dakota formation watersupplemented the daily production. Even though the initial injection water wasof lower salinity than the formation water, the entire waterflood system wasdesigned for severe service in anticipation of flood response. All vessels, tanks, injection lines, and tubing strings were protected with an internalcoating or lining. As expected, the produced water volume began increasing(Fig. 1), and subsequently, the total dissolved solids (TDS) of the injectedfluid began to rise. The produced Heath formation water is corrosive because ofits salinity (290,000 mg/L TDS) and high dissolved CO2 content (450 ppm). Evenwhen the Dakota water is added, the resulting fluid remains corrosive. In fact, corrosion rates increase in the waterflood because of oil carryover, solids, and scale deposition from mixing the waters and the occasional oxygencontamination typical in waterfloods. There is also a slight problem withsulfate-reducing bacteria in the injection system, but very little problem isevident in the producing wells. The corrosion-related failure rate in thewaterflood system accelerated concurrently with the increase in injection-watersalinity. This paper focuses on the various causes for the injection-tubingfailure rates and the steps taken to mitigate those failures successfully. Thispaper does not discuss the chemical treating, water quality, or surfaceequipment conditions. Problems This study considers 18 injection wells with at least 240 tubing jointseach. The tubing is primarily J-55 EUE 8-round 2-3/8 or 2-7/8 in. [6.03 or 7.30cm], but several strings of C-75 and N-80 have been run. All the tubing isinternally coated or lined. Injection occurs under a packer with the annulusfilled with packer fluid. Wellhead pressures are 2,900 psig [20 MPa], and fluidtemperatures range from 70 to 130F [21 to 54C]. Relatively few tubing failureswere recorded during 1973–80. It is believed, however, that during this periodinjection wans were pulled only when absolutely necessary, such as foracidizing or cleanout. Now, injection wells are pulled as soon as a leak isnoted through an increase in annular pressure. Starting in 1979, the tubingfailure rate increased dramatically with the volume of produced water (seeTable 2 and Fig. 1). Eventually, it was determined that several mechanicalfactors combined with the corrosive nature of the system to produce prematurefailures in the coatings. The failures were divided into three areas of thetubing joint (in order of cumulative failures): at the tong or makeup marks, atthe pin ends and collars, and in the body of the tube. Economically, it isdifficult to predict the length of service to payout. An 8,000-ft [2438-m]string of J-55 8-round 2-3/8-in. [6.03-cm] internally coated tubing costs about$40,000 (1989 prices). On the basis of average maintenance costs of$4,400/pulling job and replacement cost of $155/tubing joint (average of threejoints replaced per job), the entire string should be replaced the eighth timeit is pulled for leaks. This does not imply a definite time frame for payout, however, because the frequency of failure, resulting from a combination ofmechanical damage and atmosphere-accelerated corrosion, increases each time thewell is pulled. Therefore, this study uses average time to first failureinstead of payout for comparisons. Before 1980, the average time to first recorded failure of a coated tubingstring was 48 months (Table 2), as compiled from well servicing records. Therelated work-over costs during this time were less than $50,000/yr. JPT P. 350⁁

Road Damage Externalities and Road User Charges

subsequent vehicles, and these operating costs may be an order of magnitude larger than the road maintenance costs. The paper develops a theory to handle this newly identified extemality and establishes a remarkable result. If roads are repaired when they reach a predetermined critical condition (not necessarily optimally set) and if road damage is fully attributable to traffic, then in steady state with zero traffic growth the average road damage externality is zero, and the average marginal social cost of road use is equal to the average road maintenance cost. The result holds for arbitrary road damage and vehicle damage functions. Recent empirical studies reveal that weather accounts for a significant fraction of road deterioration, and in this case the road damage externality is no longer exactly zero, but is quantitatively negligible. The appropriate road user charge now only recovers the fraction of damage attributable to traffic.

An Investigation of Idle Emissions Inspection and Maintenance at Altitude

Idle emissions inspection and maintenance was evaluated using a sample of 300 privately owned 1964 through 1973 model-year vehicles operating in the Denver metropolitan area. Ten privately owned stations, licensed by the State of Colorado to perform vehicle safety inspections, were utilized to conduct idle emissions inspection and subsequent maintenance of failed vehicles. Exhaust hydrocarbon (HC) and carbon monoxide (CO) reduction as measured by the 1975 Environmental Protection Agency (EPA) mass emission testing procedures was indicated to be 13% and 8% respectively at a 50 % rejection rate. The average maintenance cost to achieve the reduction was $11.32 per failed vehicle. The adjustment and repair procedures provided to participating garages were sufficient to achieve significant emissions reduction and training provided to garage personnel was adequate. However, several problems were experienced with station personnel relative to data transmittal and inspection pass/fail limits. Problems were also e...

Pumping Plant Operation and Maintenance Costs

Procedures for preliminary estimates of annual operation and maintenance (O and M) costs of pumping plants through 15,000 hp have been developed from studies of 174 installations. They cover direct O and M costs for pumps, motors, accessory electric equipment, miscellaneous equipment, and plant structures. Intake channel, discharge line, substation, powerline, and certain replacement costs, as well as general administrative expenses, should be estimated separately. Operation and maintenance costs are considered separately. Factors affecting operation costs are degree of attendance, plant size, and operating season length. Maintenance costs depend on plant size, annual volume of water pumped, and plant age. These plant size groups were used: (1) 5 hp to 149 hp, (2) 150 hp to 6,999 hp, and (3) 7,000 hp to 15,000 hp. Maintenance costs for Group 1 are so affected by plant size that other factors are not important, but for Groups 2 and 3, the annual volume of water pimped is significant. To eliminate plant age factor, a 17-yr age representing average maintenance costs was substituted in the equations. Nomographs are included to simplify solutions of estimating equations.

Dental Caries and the Pediatrician

To the Editor: The editorial Dental Caries and the Pediatrician, which appears in the August, 1963, issue, evidences an uninformed and seriously biased grasp of the prevention of dental caries by water fluoridation issue. That such an editorial should appear in a responsible journal is indeed regrettable. The economics of the matter is that the average maintenance cost of fluoridating a water supply is ten cents per person per year. The reduction in caries makes this the best health bargain available today and far less expensive than providing pills. The cogent reasons cited demonstrate most plainly that Dr. Black has not dealt responsibly with the literature: Many careful dietary and metabolic studies have been done. They clearly outline the parameters of human safety as regards fluoride, and provide the accuracy which permits the safe fluoridation of water supplies. Concentrations of 1 ppm are harmless to older children and

Top-Contact Unprotected Conductor Rail for 600-Volt Traction Systems

The paper treats of the various factors which enter into consideration in the design of a 600-volt contact rail system. The weight of rail to be used depends upon conditions met with in each case, but in general, a heavy rail is preferable from all points of view. The question of quality is rather indeterminate, but in general, it is not advisable to use soft steel until the weight has been brought up to at least 80 lb. (36.28 kg.) per yard; however, consideration should be given to it above this weight. Insulating and supporting is a mechanical problem which must be decided upon local conditions. The method of bonding and jointing to be used depends upon size and section of rail used. With standard rail sections the foot bond is the most satisfactory, and with special sections of rail a copper welded joint will be very satisfactory. Provision must be made to control the expansion and contraction of rail by cutting it into sections and anchoring each of these sections. Various methods of connecting rails are described, together with special devices which will be required. The costs of constructing a single-track mile of contact rail using 50-lb. (22.68 kg.) rail is $3,284.29, while the cost of the same amount of 80-lb. (36.28 kg.) rail is $4,028.55. The average maintenance cost per mile of rail, exclusive of entire renewal, is $80.00 per mile per year.

Top contact unprotected conductor rail for 600 volt traction systems

The paper treats with the various factors which enter into consideration in the design of a 600 volt contact rail system. The weight of rail to be used depend upon conditions met with in each case, but in general, a heavy rail is preferable from all points of view. The question of quality is rather indeterminate, but in general, it is not advisable to use soft steel until the weight has been brought up to at least 80 lb. (36.28 kg.) per yard, however, consideration should be given to it above this weight. Insulating and supporting is a mechanical problem which must be decided upon local conditions. The method of bonding and jointing to be used depends upon size and section of rail used. With A. S. C. E. standard, the foot bond is the most satisfactory, above this weight and with special sections of rail a copper welded joint will be very satisfactory. Provisions must be made to control the expansion and contraction of rail by cutting it into sections and anchoring each of these sections. Various methods of connecting rails are described together with special devices which will be required. The costs of constructing a single track mile of contact rail uisng 50 lb. (22.68 kg.) rail is $3,284.29 while the cost of the same amount of 80 lb. (36.28 kg.) rail is $4,028.55. The average maintenance cost per mile of rail, exclusive of entire renewal, is $80.00 per mile per year.