closes OHDSI/Themis#126

Author: clairblacketer

inst/csv/OMOP_CDMv5.3_Field_Level.csv

@@ -25,7 +25,7 @@ observation_period,period_type_concept_id,Yes,integer,"This field can be used to
 visit_occurrence,visit_occurrence_id,Yes,integer,Use this to identify unique interactions between a person and the health care system. This identifier links across the other CDM event tables to associate events with a visit.,This should be populated by creating a unique identifier for each unique interaction between a person and the healthcare system where the person receives a medical good or service over a span of time.,Yes,No,NA,NA,NA,NA,NA
 visit_occurrence,person_id,Yes,integer,NA,NA,No,Yes,PERSON,PERSON_ID,NA,NA,NA
 visit_occurrence,visit_concept_id,Yes,integer,"This field contains a concept id representing the kind of visit, like inpatient or outpatient. All concepts in this field should be standard and belong to the Visit domain.","Populate this field based on the kind of visit that took place for the person. For example this could be ""Inpatient Visit"", ""Outpatient Visit"", ""Ambulatory Visit"", etc. This table will contain standard concepts in the Visit domain. These concepts are arranged in a hierarchical structure to facilitate cohort definitions by rolling up to generally familiar Visits adopted in most healthcare systems worldwide. [Accepted Concepts](https://athena.ohdsi.org/search-terms/terms?domain=Visit&standardConcept=Standard&page=1&pageSize=15&query=).",No,Yes,CONCEPT,CONCEPT_ID,Visit,NA,NA
-visit_occurrence,visit_start_date,Yes,date,"For inpatient visits, the start date is typically the admission date. For outpatient visits the start date and end date will be the same.","When populating VISIT_START_DATE, you should think about the patient experience to make decisions on how to define visits. In the case of an inpatient visit this should be the date the patient was admitted to the hospital or institution. In all other cases this should be the date of the patient-provider interaction.",No,No,NA,NA,NA,NA,NA
+visit_occurrence,visit_start_date,Yes,date,"For inpatient visits, the start date is typically the admission date. For outpatient visits the start date and end date will be the same.","When populating VISIT_START_DATE, you should think about the patient experience to make decisions on how to define visits. In the case of an inpatient visit this should be the date the patient was admitted to the hospital or institution. In all other cases this should be the date of the patient-provider interaction. If this information is not available the record should be dropped.",No,No,NA,NA,NA,NA,NA
 visit_occurrence,visit_start_datetime,No,datetime,NA,"If no time is given for the start date of a visit, set it to midnight (00:00:0000).",No,No,NA,NA,NA,NA,NA
 visit_occurrence,visit_end_date,Yes,date,For inpatient visits the end date is typically the discharge date.,"Visit end dates are mandatory. If end dates are not provided in the source there are three ways in which to derive them:
 - Outpatient Visit: visit_end_datetime = visit_start_datetime

inst/csv/OMOP_CDMv5.4_Field_Level.csv

@@ -25,7 +25,7 @@ observation_period,period_type_concept_id,Yes,integer,"This field can be used to
 visit_occurrence,visit_occurrence_id,Yes,integer,Use this to identify unique interactions between a person and the health care system. This identifier links across the other CDM event tables to associate events with a visit.,This should be populated by creating a unique identifier for each unique interaction between a person and the healthcare system where the person receives a medical good or service over a span of time.,Yes,No,NA,NA,NA,NA,NA
 visit_occurrence,person_id,Yes,integer,NA,NA,No,Yes,PERSON,PERSON_ID,NA,NA,NA
 visit_occurrence,visit_concept_id,Yes,integer,"This field contains a concept id representing the kind of visit, like inpatient or outpatient. All concepts in this field should be standard and belong to the Visit domain.","Populate this field based on the kind of visit that took place for the person. For example this could be ""Inpatient Visit"", ""Outpatient Visit"", ""Ambulatory Visit"", etc. This table will contain standard concepts in the Visit domain. These concepts are arranged in a hierarchical structure to facilitate cohort definitions by rolling up to generally familiar Visits adopted in most healthcare systems worldwide. [Accepted Concepts](https://athena.ohdsi.org/search-terms/terms?domain=Visit&standardConcept=Standard&page=1&pageSize=15&query=).",No,Yes,CONCEPT,CONCEPT_ID,Visit,NA,NA
-visit_occurrence,visit_start_date,Yes,date,"For inpatient visits, the start date is typically the admission date. For outpatient visits the start date and end date will be the same.","When populating VISIT_START_DATE, you should think about the patient experience to make decisions on how to define visits. In the case of an inpatient visit this should be the date the patient was admitted to the hospital or institution. In all other cases this should be the date of the patient-provider interaction.",No,No,NA,NA,NA,NA,NA
+visit_occurrence,visit_start_date,Yes,date,"For inpatient visits, the start date is typically the admission date. For outpatient visits the start date and end date will be the same.","When populating VISIT_START_DATE, you should think about the patient experience to make decisions on how to define visits. In the case of an inpatient visit this should be the date the patient was admitted to the hospital or institution. In all other cases this should be the date of the patient-provider interaction.  If this information is not available the record should be dropped.",No,No,NA,NA,NA,NA,NA
 visit_occurrence,visit_start_datetime,No,datetime,NA,"If no time is given for the start date of a visit, set it to midnight (00:00:0000).",No,No,NA,NA,NA,NA,NA
 visit_occurrence,visit_end_date,Yes,date,"For inpatient visits the end date is typically the discharge date.  If a Person is still an inpatient in the hospital at the time of the data extract and does not have a visit_end_date, then set the visit_end_date to the date of the data pull.","Visit end dates are mandatory. If end dates are not provided in the source there are three ways in which to derive them:
 - Outpatient Visit: visit_end_datetime = visit_start_datetime