Provider Update

Volume 21, Issue 1 

January/February 2004

Long Term Personal Care Services  Notice of Intent to Establish Hospice as an Ongoing Medicaid Program
Clarification of Crown Services Policy Procedure Code Additions for DME
Referral for Pregnancy Related Dental Services KM-3 Encounter Procedure Code - RHC/FQHC
New CPT Code Becomes Payable EDI/EMC Cutoff Clarification
Changes to Payable Injections Policy New Reimbursement Methodology

LADUR Education Article

Long Term Personal Care Services Program Announced

The Department of Health and Hospitals, Bureau of Health Services Financing announces the start of a new optional service program under the Medicaid Program. This services program is called Long Term Personal Care Services (LT-PCS) and is intended to provide personal care assistance to qualified Medicaid recipients so that they may continue to live in their own homes. The LT-PCS Program is designed to supplement existing family and/or community supports that are available to maintain the recipient in the community; it is not a substitute for these supports. This program will provide assistance to qualified Medicaid recipients who need help with one or more activities of daily living such as eating, grooming, bathing, ambulation, dressing, and toileting.

In order to qualify for the LT-PCS Program, an individual must be a Medicaid recipient who is age 65 or older, or age 21 or older with disabilities. Disabled is defined as meeting the eligibility criteria established by the Social Security Administration. The disability must meet the Social Security definition or criteria for disability as defined by the Social Security Administration. In addition, the recipient must meet the medical standards for admission to a nursing facility, be able to participate in his/her care and direct the services provided by the personal care worker independently or through a responsible representative.

The LT-PCS Program is not a sitter or maid service and does not provide supervision for an individual who cannot be left at home alone. This program does not include the following services: medication administration, skilled nursing services, supervision, rehabilitative services, general housekeeping, or respite for the primary care giver.

In order to participate as a provider in the LT-PCS Program, an agency must have a current, valid Personal Care Attendant license issued by the Department of Social Services. If you wish to enroll to participate as a provider in the LT-PCS Program, you may call Unisys Provider Relations at (225) 924-5040 or 
1-800-473-2783 for a provider enrollment packet. Medicaid recipients may be referred to Affiliated Computer Services (ACS) at 1-866-229-5222 to receive information regarding the LT-PCS Program.

Clarification and Revision of Crown Services Policy 

Effective immediately, the following policy clarification and revision will be applicable for crown services. 

Policy Clarification - Crown services require radiographs, photographs, other imaging media or other documentation which depict the pretreatment condition. The documentation that supports the need for crown services must be available for review by the Bureau or its designee upon request.

Policy Revision - The following policy revision is specific the to procedure code D2930 (Prefabricated Stainless Steel Primary tooth). 

Stainless steel crowns (D2930) may be placed on primary teeth that exhibit any of the following indications, when failure of other available restorative materials is likely to occur prior to the natural shedding of the tooth:

  • extensive caries;

  • interproximal decay that extends into the dentin;

  • significant observable cervical decalcification; 

  • significant observable developmental defects, such as hypoplasia and hypocalcification.

  • following pulpotomy or pulpectomy;

  • restoring a primary tooth that is to be used as an abutment for a space maintainer; or,

  • fractured tooth. 

Additionally, a stainless steel crown may be authorized to restore an abscessed primary 2nd molar, in conjunction with a pulpectomy prior to the eruption of the permanent 1st molar in order to avoid placement of an indicated distal shoe space maintainer.

Stainless steel crowns are not medically indicated and reimbursement will not be paid in the following circumstances:

  • primary teeth with abscess or bone resorption; or

  • primary teeth where root resorption equals or exceeds 75% of the root; or

  • primary teeth with insufficient tooth structure remaining so as to have a poor prognosis of 
    success, i.e. unrestorable; or 

  • incipient carious lesions 

If you have any questions regarding this matter, you may contact the Dental Medicaid Unit by calling 504-619-8589.

Referral for Pregnancy Related Dental Services (BHSF-Form 9-M) 
Policy Clarification and Form Revision Notice

The BHSF Form 9-M is the referral form that is used to verify pregnancy for the Expanded Dental Services for Pregnant Women (EDSPW) Program. This referral form also provides additional important information. 

The recipient is required to obtain the original completed BHSF Form 9-M from the medical professional providing her pregnancy care and give it to the dentist prior to receiving dental services. Prior to rendering any services, the dental provider must have the original BHSF Form 9-M with the signature of the medical professional providing the pregnancy care. Facsimile copies are not acceptable. The original form must be kept in the recipient's dental record. A copy of this form must be submitted to the Medicaid Dental Prior Authorization Unit when requesting authorization for any EDSPW Program services that requires prior authorization.

The BHSF Form 9-M, issue date 11/03, was distributed to obstetricians/gynecologists and other medical professionals who provide pregnancy care as well as to all dental providers. This form has recently been revised with an issue date of 12/03 and will be mailed to the above mentioned providers as soon as possible. It will also be available on the LA. Medicaid website. Effective April 1, 2004, providers must use the revised form with the date issue 12/03. Blank forms may be photocopied for distribution as needed. Additional copies of this form may also be requested by calling Unisys Provider Relations at (800) 473-2783 or Medicaid (225) 924-5040. If you have any questions regarding this matter, you may contact the Medicaid Dental Unit by calling 504-619-8589.

New CPT Code Becomes Payable

Effective for dates of service on or after November 1, 2003, the following CPT procedure codes were added to the list of codes payable to podiatrists:

15342 - Application of bilaminate skin substitute - 25 sq cm
20694 - Removal of external fixation system

New Reimbursement Methodology 

All providers should have submitted Inventories for Clients and Agency Planning (ICAPs) and the Louisiana Level of Need Survey (LA-LONS) for all facility residents to Rate and Audit Review. The initial data set is being used to calculate rates using the new reimbursement methodology. 

In the January 2004 Louisiana Register, further direction is given to providers during this transition to the new reimbursement methodology. Providers must update the ICAP and LA-LONS at the time of the resident annual evaluation on an on-going basis. Health Standards is given the authority to review the ICAP and LA-LONS prior to the proposed July 1, 2004 implementation of this project. This review by Health Standards will allow providers several months to become accustomed to completing the ICAP correctly.

Providers should update the ICAP in the ICAP computer program. When updating the ICAP, the evaluation date must be updated to reflect the new evaluation date. All previous directions for completing the ICAP should be followed. These instructions were mailed to all facilities in July 2003. 

Provider are not required to submit the updated ICAP data to the Rate and Audit Review Section at this time. You will receive further instructions on submitting the updated ICAPs in the near future. If you have questions, you may call Mary Norris at 225-342-2768. 

Changes to Payable Injections Policy

Rhogam injections - CPT procedure code 90742 must be used to bill for dates of service prior to May 1, 2003. For dates of service May 1, 2003 and after, CPT code J2790 should be used. It is necessary that the recipient must have an Rh factor diagnosis (diagnosis of pregnancy is insufficient) in order to receive payment for these codes.

Depo-Provera, 150 mg - CPT procedure code J1055 must be used to bill this service. This procedure code should only be used for contraception. It is restricted to one injection every three months for females between the ages of 10 and 55

Depo-Provera, 1000mg/2.5 ml - CPT procedure code J9162 must be used to bill for dates of service prior to October 1, 2003. For dates of service October 1, 2003 and after, CPT code J1051 should be used. This procedure code should only be used for cancer treatment.

Lunell injections - CPT procedure code Z9921 must be used to bill for dates of service prior to August 1, 2002. For dates of service August 1, 2002 and after, provider should bill with CPT code J1056.

Mirena injections - CPT procedure code J7302 must be used to bill for the device and CPT code 11981 for the implantation. It is restricted to one every 7 years for females between the ages of 10 and 60.

Intrauterine Copper Contraceptive - CPR Procedure X0516 must be used to bill for dates of service prior to October 1, 2002. For dates of services after October 1, 2002, CPT code J7300 for the device and CPT code 58310 for the implantation. It is restricted to one every 7 years for females between the ages of 10 and 60. 

All other parts of this policy remain unchanged.

Notice of Intent to Establish Hospice as Ongoing Medicaid Program

A Notice of Intent will be published in the February 2004 Louisiana Register proposing to establish hospice care as an ongoing Medicaid service program. It was established July 1, 2002 as a pilot program. Over the past 18 months, enrollment of hospice providers has increased to 58 and they are providing hospice services to 1,825 Medicaid recipients. During the pilot program DHH has encountered the following problems:

1. Education of hospice providers. Hospice Provider Training is provided by DHH's fiscal intermediary, Unisys, but attendance at the trainings has been low.
2. Timely submission of Election and Certification of Terminal Illness Forms.
3. Hospice recipients are encouraged to revoke hospice when they have an inpatient admission and re-elect hospice after discharge from the hospital. This is against Medicaid Hospice Policy.
4. Timely submission of prior authorization requests before the recipients' initial 180 days have expired.
5. Determining if services are being duplicated for Medicaid recipients under Waiver and Hospice Programs.

Procedure Code Additions for DME Program

Payment for both open and closed system suction catheters are currently being authorized by the Unisys Prior Authorization Unit and billed using procedure code A4624. Payment for facial prosthetics are being authorized and billed using procedure code L8499.

We have identified valid, HIPAA compliant procedure codes that are more appropriate. We have placed these codes in pay status effective January 1, 2004. Providers should begin using these codes immediately, as appropriate.

Procedure code A4609 should be used for a tracheal suction catheter for less that 72 hours use in a closed system. The reimbursement fee is $10.01 per catheter. Procedure code A4610 should be used for a tracheal suction catheter for 72 hours or more of use. The reimbursement fee is $15.64 per catheter. Procedure code A4624 should be used for a tracheal suction catheter, any type other than a closed system. The reimbursement rate is $1.76 per catheter.

Procedure code L8040 should be used for a nasal prosthesis. The reimbursement rate is $1, 352.99 for the initial fitting, $1,285.34 for a replacement including new impression, moulage, and $541.18 for a replacement using a previous master model. Procedure code L8041 should be used for a midfacial prosthesis. The reimbursement includes new impression/moulage is $541.18 for a replacement using a previous master model.

Procedure code L8042 should be used for an orbital prosthesis. The reimbursement rate is $1,832.37 for the initial fitting, $1,740.75 for a replacement including new impression/moulage, and $732.95 for a replacement using a previous master model.

KM-3 Encounter Procedure Code - RHC/FQHC

Effective May 1, 2003, KidMed claims for screening services from Rural Health Clinics (RHC) and Federally Qualified Health Centers (FQHC) billed on the KM-3 must include an Encounter Procedure Code (T1015) as well as the codes for the screening services performed. Providers are reimbursed the provider performed specific PPS visit rate for the encounter and the screening services are paid $0.00. Screening services by an RHC/FQHC provider that are billed without an Encounter Code are denied with edit 136 (no eligible service paid/encounter denied). Likewise, Encounter Code T1015 billed without a KIDMED Medical Screening is denied with edit 136. Hearing and vision screening services are not payable if performed separately from a medical screening and will deny for error edit 136 if the medical screening and encounter are not billed.

KIDMED screening claims are subject to initial data editing in the Louisiana KIDMED EPSDT Information System prior to being released to the regular Medicaid claims processing system (LMMIS). When partial claim lines from RHC/FQHC providers are held in the KIDMED System and the remaining partial claim lines are released to LMMIS, the LMMIS edit requirements described above may not be met, resulting in denied claims.

In order to process all lines of a claim together, KIDMED screening claims from RHC & FQHC providers will now be released to LMMIS or returned to the provider (rejected or denied) as a package. If all claim detail lines are approved by the KidMed System, the entire claim will be released to LMMIS. On the other hand, if any line on the claim is pended, rejected or denied, all lines on the claim will be pended, rejected or denied in the KIDMED System. A new KIDMED System error code, 517 (Prevent RHC/FQHC Claim Separation) will be assigned to those claim lines pended, rejected, or denied simply to keep the claim intact. 

Only the claim line(s) with a standard error code will be returned to providers on the Resubmittal Turnaround Document (CP-0-50) and require correction by the provider. Any other accompanying claim lines pending for error code 517 will be released automatically when the rejected claim line(s) are corrected and returned to Unisys.

The Denied Claims List (CP-0-50) will list all claim lines denied; some lines will reflect standard deny codes and some will have the new error code 517. The standard denial code will reflect what action needs to be taken by the provider and then all claim lines should be resubmitted if resubmittal is appropriate.


EDI/EMC cutoffs are the same for both proprietary and HIPAA specifications.

Tapes and diskettes - cutoff is Wednesday at 5:00 p.m.
KIDMED - cutoff is Wednesday at 4:30 p.m.
Telecommunication - cutoff is Thursday at 10:00 a.m.

Please be aware of these cutoffs to ensure that your transmissions are processed each week.

Louisiana Drug Utilization Review (LADUR) Education

Inappropriate Prescribing in the Elderly

By: Melissa L. Dear, BS Pharm
Assistant Director, Prior Authorization
Office of Outcomes Research and Evaluation
School of Pharmacy
University of Louisiana at Monroe


� Inappropriate prescribing in the elderly has become a growing clinical dilemma.

� Seventeen percent (17%) of hospitalizations in elderly patients are due to adverse drug reactions.

� The Beers criteria have been the most widely used for assessing inappropriate prescribing in the elderly.


As the elderly population continues to rise, inappropriate prescribing in the elderly has become a growing clinical dilemma. Although patients over the age of 65 constitute only 12.5% of the entire U.S. population, nearly 30% of the nation's health care expenditures are generated from this age group.[1] Seventeen percent (17%) of hospitalizations in elderly patients are due to adverse drug reactions (ADRs).[2] The increased risk of ADRs in this age group is due to a number of factors, including poor health status, increased number of medical conditions, increased number of prescriptions, and inappropriate prescribing.[1] Approximately one-fifth of the elderly are given medications considered inappropriate for their age.[2] Potentially inappropriate medications are those for which the risk to the patient outweighs the benefit.[3] For example, a medication would be considered inappropriate if a proven, more effective alternative is available, or if it has a serious potential for an adverse drug reaction which could possibly lead to hospitalization or death.[4]

Beers et al identified a need for established guidelines on inappropriate medication use in the elderly, and made the first attempt to establish these guidelines in an effort to improve physician prescribing patterns.[5] The guidelines were developed in 1991 in the form of explicit criteria, and then updated in 1997 to include additional patient settings, diagnosis-specific criteria, and severity ratings.[5, 6] Other criteria were also developed, but most resulted in a variation of the original Beers list. One of these studies conducted by Stuck et al focused on community-dwelling elderly. Their results consisted of a modified list very similar to the original, with the exception of methyldopa and propranolol.[7] The Beers criteria have definitely been the most widely used for assessing inappropriate prescribing in the elderly, and will be the focus of this article. Risk factors, prevalence, and examples of inappropriate medications will also be discussed. 

Beers Studies

In 1991, Beers et al developed the first set of criteria for determining inappropriate medication use in nursing home residents over the age of 65. After conducting a comprehensive literature review, a survey instrument was developed containing the guidelines found on inappropriate medication use. A two-round survey based on Delphi methods was used. This survey was given to a panel of experts in psychopharmacology, pharmacoepidemiology, clinical geriatric pharmacology, general clinical geriatrics, and long-term care. A total of 13 experts completed the process. The group reached consensus on 30 factors defining inappropriate use. Nineteen of these described medications that should generally be avoided in the nursing home population, and 11 described doses, frequencies, or durations of medications that should generally not be exceeded.[5] 

Since the 1991 Beers study was developed using the opinions and information available at that time, it was obvious that a revision would be necessary as new medications and updated information became available. Also, expansion was required to include clinical variables, such as diagnosis and disease severity. Since the original criteria did not consider these clinical aspects, they were limited in their application. Furthermore, despite the fact that the original criteria were developed for nursing home residents, they were being applied to elderly people in the community setting. This demonstrated a need to expand the criteria to include the elderly in settings outside the nursing home.[5, 6]

The original criteria were updated in 1997 by Beers. Focusing only on articles published after the original study in 1991, a literature review was conducted to locate relevant articles on medication use in the elderly. Using the original criteria and the results of the literature search, Beers developed statements on the inappropriate use of medication in the elderly. There were 3 types of statements:

� Medications that should be avoided in the elderly because they are either ineffective or pose 
unnecessarily high risks.
� Doses, frequencies, or durations of therapies of certain medications that govern the appropriate 
use in elderly patients.
� Medications that should not be used in elderly patients with certain medical conditions.

Six nationally recognized experts in geriatric care and pharmacology were asked to evaluate the statements. Reviewers rated the validity of each statement and also rated the severity of any problems that may arise associated with the medication.[6] 

There were several differences between the original criteria and the updated criteria. Unlike the original criteria, which were developed for nursing home patients, the new guidelines were meant to be applied to a population of patients over age 65 years, regardless of their place of residence. Another distinguishing factor was that the new criteria assigned a relative rating of severity to each criterion and provided guidelines concerning the usage of certain medications in elderly patients with specific diagnoses. Also, they included new products and updated information about existing medications.[6]

Table 1, which summarizes the results of both the 1991 and 1997 Beers studies, outlines the medications to avoid or use within specified doses or durations in elderly patients.[5, 6, 8] The medications that should be avoided in elderly patients with specific disease states are listed in Table 2.[6, 8]

Risk Factors 

Several studies have been conducted using the Beers criteria to examine inappropriate medication use by the elderly in a number of different settings. These studies have shown that there are several risk factors for receiving inappropriate medications.[1] Patients with the following characteristics were shown to be at greater risk: 

� Increased number of prescriptions
� Prescriptions for certain medications (such as antianxiety agents, sedatives, antidepressants, or analgesics)
� Poor health status
� Certain demographics (female, ages 65 - 84, residing in a rural area)

An increased number of prescriptions is probably the most significant predictor of inappropriate medication use.[7, 9-11] With each additional prescription, the odds of an elderly person being prescribed an inappropriate medication increase by 22%.[10] Studies have shown that patients are six times more likely to be prescribed an inappropriate medication if they are in poor health or if they have prescriptions from certain drug classes such as antianxiety agents, sedatives, antidepressants, or analgesics.[10, 11]

Demographics of the elderly population are also a factor to consider. Surprisingly, a study conducted in nursing home patients found that residents ages 65 -84 were prescribed inappropriate medications more frequently than those ages 85 and older. This could possibly be due to the fact that physicians are more cautious when prescribing to patients in this age group.[12] Females and patients living in rural areas also have a greater risk of receiving an inappropriate medication.[10-12] 

Table 1. Medications to avoid or use within specific does/duration in elderly patients


The prevalence of inappropriate prescribing seems to be highest in the elderly nursing home population. In a 1992 study conducted in nursing home residents, 40.3% of the participants were receiving at least one inappropriate medication.[12] The next highest percentage was found in patients residing in assisted living facilities with 28.8% of them using one or more medications considered inappropriate.[13] The studies conducted in community-residing elderly resulted in a range of 14% to 27% of the participants receiving inappropriate meds.[7, 9, 11] The difference in the prevalence of inappropriate prescribing in the community elderly could be due to a number of factors, such as the version of the criteria used, time period of the study, and method of data collection. 

Some of the most commonly prescribed inappropriate medications identified in the studies were the long-acting benzodiazepines, propoxyphene, and amitriptyline.[7, 9-11, 14]


With the large prevalence of inappropriate prescribing in elderly patients, one could assume that this would lead to poor health outcomes. However, in a study conducted by Hanlon et al that evaluated the relationship between the use of inappropriate drugs according to the Beers criteria and mortality and functional status, the use of inappropriate medications was not significantly associated with mortality or decline in functional status.[15] Another study examining the impact of inappropriate prescribing in nursing home patients also found that there was no association between inappropriate prescribing and mortality rates. However, this study did identify a positive relationship between the cost of pharmaceutical services and the number of inappropriate medications prescribed.[16]

Most of the studies conducted on inappropriate prescribing do not address the outcomes associated with prescribing inappropriate medication to elderly patients.[1] Without addressing this important aspect, it cannot be determined whether or not an adverse outcome actually occurred as a result of the medication. The seriousness of the outcome could also vary widely. Adverse reactions could range from serious events such as falls, fractures, or death to less severe outcomes such as sedation, dry mouth, constipation, or urinary incontinence. While the latter are not as serious, they could impact the patient's quality of life and lead to further complications.[12]

Limitations of the Criteria

Although accepted by the medical community, these widely-used criteria have limitations, one of which is the fact that they do not address the individual needs of the patient. They should not be a substitute for careful clinical consideration since the criteria may not apply to every situation.[6] Also, during the development of these guidelines, the panel of experts had differences of opinion on several issues which may demonstrate a need for further study of those specific medications in elderly patients.[5] Furthermore, when using the guidelines to make clinical decisions, the most current studies on elderly medication use should also be consulted since research is an ongoing process.

Role of the Health Care Professional

Reducing drug related problems in the elderly is a difficult task, but can be accomplished with the participation of health care professionals. Although the Beers criteria address only one portion of these problems in the elderly, they have become a valuable mechanism for assessing inappropriate prescribing. Through provider education and intervention programs, such as online DURs, providers can utilize these guidelines to improve prescribing patterns in their elderly patients.[3]
Pharmacists also have a role. In July 1999, the Health Care Financing Administration implemented changes to their nursing home survey process to include drug therapy guidelines based on the 1997 Beers criteria.[13] Consultant pharmacists use these guidelines to notify physicians of potentially inappropriate medications. In the retail and hospital settings, pharmacists can alert physicians to inappropriate prescribing during the drug distribution process. By working together, health care professionals can have a positive impact on medication use in the elderly.

It is important to remember that these guidelines are simply a tool used to alert practitioners to the fact that an elderly patient is receiving a potentially inappropriate medication. The practitioner must then use professional judgment and clinical knowledge to determine the most effective drug therapy for the patient.


1. Liu, G.G. and D.B. Christensen, The Continuing Challenge of Inappropriate Prescribing in the Elderly: An Update on the Evidence. Journal of the American Pharmaceutical Association, 2002. 42(6): p.847-857.
2. Roller, K., Pharmacists Face Challenge of Surging Elderly Population. Drug Store News, 1998.
3. Aparasu, R.R. and J.R. Mort, Inappropriate Prescribing in the Elderly: Beers Criteria-Based Review. The Annals of Pharmacotherapy, 2000. 34: p. 338-346.
4. Edwards, R.F., T.M. Harrison, and S.M. Davis, Potentially Inappropriate Prescribing for Geriatric Inpatients: An Acute Care of the Elderly Unit Compared to a General Medicine Service. The Consultant Pharmacist, 2003. 18(1): p. 37-49.
5. Beers, M.H.M., et al., Explicit Criteria for Determining Inappropriate Medication Use in Nursing Home Residents. Archives of Internal Medicine, 1991. 151: p. 1825-1832.
6. Beers, M.H.M., Explicit Criteria for Determining Potentially Inappropriate Medication Use by the Elderly: An Update. Archives of Internal Medicine, 1997. 157(14): p. 1531-1536.
7. Stuck, A.E., et al., Inappropriate Medication Use in Community-Residing Older Persons. Archives of Internal Medicine, 1994. 154(19): p. 2195-2200.
8. Posey, L.M., Improving Pharmacotherapy in the Elderly: Explicit Criteria for Daily Practice. The Consultant Pharmacist, 1998.
9. Hanlon, J.T., et al., Inappropriate Drug Use Among Community-Dwelling Elderly. Pharmacotherapy, 2000. 20(5): p. 575-582.
10. Aparasu, R.R. and S.J. Sitzman, Inappropriate Prescribing for Elderly Outpatients. American Journal of Health-System Pharmacy, 1999. 56(5): p. 433-439.
11. Zhan, C.M., PhD, et al., Potentially Inappropriate Medication Use in the Community-Dwelling Elderly: Findings from the 1996 Medical Expenditure Panel Survey. Journal of the American Medical Association, 2001. 286(22): p. 2823-2829.
12. Beers, M.H., et al., Inappropriate Medication Prescribing in Skilled Nursing Facilities. Annals of Internal Medicine, 1992. 117(8): p. 684-689.
13. Rhoads, M. and A. Thai, Potentially Inappropriate Medications Ordered for Elderly Residents of Assisted Living Homes and Assisted Living Centers. The Consultant Pharmacist, 2002. 17(7): p. 587- 593.
14. Aparasu, R.R. and J.R. Mort, Prescribing Potentially Inappropriate Psychotropic Medications to the Ambulatory Elderly. Archives of Internal Medicine, 2000. 160(18): p. 2825-2831.
15. Hanlon, J.T., et al., Impact of Inappropriate Drug Use on Mortality and Functional Status in Representative Community Dwelling Elders. Medical Care, 2002. 40(2): p. 166-176.
16. Gupta, S., H.M. Rappaport, and L.T. Bennett, Inappropriate Drug Prescribing and Related Outcomes for Elderly Medicaid Beneficiaries Residing in Nursing Homes. Clinical Therapeutics, 1996. 18(1): p. 183-196.