Concept: Ambulatory Visits

Introduction

This concept provides information on the current definition and method used at MCHP for defining ambulatory visits by a physician, based on data contained in the MCHP Data Repository. The methodology for identifying ambulatory visits underwent a major change in 2012, based on changes in the Medical Services data being collected by Manitoba Health.

This concept contains a definition of ambulatory visits; provides information about the reasons for the change in methodology and internal access only to the previous method (now archived) of identifying ambulatory visits; describes the current method of identifying ambulatory visits in MCHP research; identifies the current SAS® macro that is available for identifying ambulatory visits; and describes some of the variations from the general definition of ambulatory visits that have been used in MCHP research over time.

The term "Ambulatory Visits - Physician" has also been called Ambulatory Visits, Ambulatory Physician Visits, Physician Claims and Physician Visits in MCHP research.

Note: This concept was originally called Ambulatory Visits – Physician but was changed to Ambulatory Visits because MCHP research has started identifying types of providers. Methods of identifying the different types of providers are described below.

Definition of Ambulatory Visits

A very simple definition of an ambulatory visit is ... "visits to a licensed physician in an outpatient setting in Manitoba." (Katz et al., 2014). A physician can be a Family Physician (FP) or a specialist physician. Outpatient settings generally include office visits, walk-in clinics, home visits, personal care home (PCH)/nursing home visits and visits to outpatient departments in a hospital. Visits to patients who are inpatients (admitted to an acute care hospital) are not considered ambulatory visits. Outpatient surgeries, diagnostic tests and procedures are also not considered ambulatory visits.

Data Source for Ambulatory Visits

Ambulatory Visits can be extracted from the Medical Services (Physician Claims) data. The Hospital Abstracts data are also used to identify physician services that are provided to patients who are admitted to acute care hospitals, so these inpatient visits are not included as ambulatory visits.

The specific type of physician service provided during an ambulatory visit is defined by a 4-digit tariff code recorded in the Medical Services data. For a sample of some of the tariff codes, please see the MCHP Documentation - tariff_serv_type.txt document in the LINKS section below.

Reason For Change in Methodology

As mentioned, the methodology used to identify ambulatory visits was revised in 2012 based on a change in the Medical Services (Physician Claims) data. At that time, the variable Pattern of Practice, used in the "old" method of defining ambulatory visits was no longer being consistently recorded in the data. This change required MCHP to review and revise its' methodology for identifying ambulatory visits.

The information previously contained in this concept, including the use of Pattern of Practice codes, is no longer current in light of the new method developed for identifying ambulatory visits. However, the previous concept information is archived for historical purposes in case it is ever needed for referral or is needed to replicate results achieved in past research. The archived concept content - Ambulatory Visits - Physician - ARCHIVED (internal access only) - is available in the LINKS section below.

Method of Identifying Ambulatory Visits - Physician

The method for identifying ambulatory visits from the Medical Services (Physician Claims) data was revised in 2012. This method includes a number of "data conditions" that will either include or exclude specific types of services from the ambulatory visits definition. In summary, these conditions are:


1. Include only those records with the tariff prefix, PREFIX = "7". These are defined as "Visits, Calls and Special Tests" in the Medical Services data.
   
   
2. Include records that have one of the following Manitoba Grouping Code (MGC) values, classified as "Office Visits":

   001 - major /initial,
   002 - other consultations,
   003 - complete exam - initial,
   004 - complete exam - other,
   005 - partial / minor / subsequent visit,
   006 - regional history & visit,
   007 - intermediate visit,
   008 - psychotherapy,
   009, 010, and 011 - currently these values are not defined in the MGC group of codes, but fall within the category of "Office Visits", and
   012 - other office visits

   ... as well as the following MGC codes:

   013 - hospital visits - unassigned patient,
   016 - hospital visit - chronic / palliative care, and
   075 - obstetrical services - prenatal & postnatal visits.

3. Exclude a visit if it happens during an inpatient hospital stay, identified using the hospital abstracts data. A visit on the day of admission or discharge, or in between these two dates is excluded.
   
   
4. Exclude certain types of providers using the variable MDBLOC with the following values:

   "053" - E.E.N.T - optometry,
   "200" - Primary Care Nurse,
   "201" - Midwife,
   "99" - Unspecified or unknown
   "113" - Emergency Medicine

5. Exclude Emergency Room services using the variable OPD with the following value: "E" - Emergency Room Services.
   
   
6. Exclude Out of Province (OOP) claims, identified by the 3rd character in MDBLOC = "9".
   
   
7. Exclude diagnoses beginning with "A", "B", or "C", which are associated with chiropractic claims.

Methods of Identifying Provider Types

Ambulatory visits in MCHP research has identified different provider types.


1. Ambulatory Visits - Physician – see above
   
   
2. Ambulatory Visits to Specialists is the number of ambulatory visits to specialist physicians such as all internal medicine specialists, pediatricians,psychiatrists, obstetricians & gynecologists, and surgeons.
   
   Katz et al. (2019) identified Ambulatory Visits to Specialists as follows:
   
   
   1. Included outpatient contacts with the following specialist physicians (based on MDBLOC values):

      12 - Physical Medicine & Rehab,
      129 - Physical Medicine - OOP,
      130 - Internal Medicine - Career Medical Scientist,
      131 - Internal Medicine - Endocrinology,
      132 - Internal Medicine - Haematology,
      133 - Internal Medicine - Infectious Disease,
      134 - Internal Medicine - Respiratory,
      141 - Surgery - Vascular,
      142 - Surgery - Thoracic,
      143 - Surgery - Paediatric General,
      15 - Oncology,
      150 - Oncology - Medical,
      151 - Oncology - Gynaecological,
      152 - Oncology - Urological,
      153 - Oncology - Paediatric,
      154 - Oncology - Community,
      155 - Oncology - ?,
      156 - Oncology - ?,
      158 - Oncology - Radiology

   2. Excluded Visits to primary care providers, pathologists and radiologists.
      
      Sources: Ambulatory Specialist Visits from Katz et al. (2019) deliverable and Technical Definitions of Indicators and Drug Codes from online supplement material from Katz et al. (2019).
   
   
3. Ambulatory visits - Primary Care Provider is the number of visits to a primary care provider in an outpatient setting. In MCHP research, primary care providers include Family Physicians (FP) and Nurse Practitioners.
   
   Katz et al. (2019) identified Ambulatory Visits - Primary Care Provider by:
   
   
   1. Included visits to primary care providers (based on MDBLOC values):

      11 - General Practice,
      111 - General Practice – Metro Winnipeg/Brandon,
      112 - General Practice – Rural,
      200 - Primary Care Nurse

      Sources: Ambulatory Primary Care Visits from Katz et al. (2019) deliverable and Technical Definitions of Indicators and Drug Codes from online supplement material from Katz et al. (2019).

SAS Macro for Identifying Ambulatory Visits

The Medical Services data contains physician service claims and adjustments to the original claims. Adjustments are necessary in order to correct or adjust the number and cost of services. Please read the Costs / Fee Information section of the Physician / Hospital Claims concept for more information on costs and fees and why these adjustments are made.

MCHP has developed and uses a SAS® macro to generate consistent information about physician services over time. The current macro, called net_med.sas, is used to "net" physician claims for services and costs, and can also be used to identify ambulatory visits and services that are provided in-hospital patients. The net_med.sas macro is available in the MCHP System Macro Library. The macro has a number of different parameters that can be chosen when the macro is run, such as dates, data sets to include and whether to identify ambulatory visits and in-hospital services.

The macro parameter of type = AMBVIS will invoke the macro to identify ambulatory visits when it runs. The macro will apply the conditions described above and produce an indicator that flags a variable amb_vis = 1 that can be used to identify all ambulatory visits in the data.

For more information on the net_med SAS macro, please see the SAS code and formats (internal access only) section below.

Variation in the "Ambulatory Visits" Definition

Over time, variation in the ambulatory visits definition occurs, depending on the individual needs of the MCHP research project. The decision to include / exclude certain types of conditions is specific to the scope of the current research project and the project requirements should be reviewed prior to any investigation of ambulatory visits.

The following provides brief information on some of the variation with ambulatory visits found in MCHP research:


• In some research, ambulatory visits include emergency room visits (where data are recorded) and contact in northern/remote nursing stations. In our current method, emergency room visits have been excluded from the definition.
  
  
• In past research, prenatal care visits were typically excluded from the definition because of tariff coding issues (e.g.: global billing and not being able to identify the exact number of visits). However, specific prenatal and postnatal care visit tariff codes were introduced in February 2000, and the current ambulatory visits definition now includes prenatal and postnatal visits.
  
  
• In some research, additional exclusions are made depending on the focus of the study. For example, in Katz et al. (2013), they excluded services provided to patients admitted to personal care homes (PCH) and emergency departments, as well as visits to specialist physicians in pediatrics, radiology, pathology and anaesthesiology.
  
  
• In some research, ambulatory visits has defined provider types. For more information, see Ambulatory Visits - Primary Care Provider / Ambulatory Primary Care Visits and Ambulatory Visits to Specialists/ Ambulatory Specialist Visits .

Other Notes

• Consultations that occur in an outpatient setting are considered ambulatory visits.
  
  
• For ambulatory visits that occur in a Personal Care Home (PCH), a note is written to the net_med SAS macro log file that identifies that there are ambulatory visits in a PCH setting. PCHs can be identified by the following range of values (500 - 699) in the HOSP variable in the Medical Services data.
  
  
• Nurse Practitioners started being recorded in Medical Services Data in 2005.