Surge in US Outpatient Vitamin D Deficiency Diagnoses: National Ambulatory Medical Care Survey Analysis

Karen E. Huang, MS; Brandy-Joe Milliron, PhD; Scott A. Davis, MA; Steven R. Feldman, MD, PhD

Disclosures

South Med J. 2014;107(4):214-217. 

In This Article

Abstract and Introduction

Abstract

Objectives: In light of the growing medical interest in the potential consequences of vitamin D deficiency, it is important that clinicians are informed about the varying factors that may complicate the assessment of vitamin D status and the diagnosis of deficiency. To better understand the frequency of vitamin D deficiency diagnoses in the ambulatory setting over time, the objective of this investigation was to examine unspecific, general, and bone-related vitamin D deficiency diagnoses between 2007 and 2010 and to determine whether the rate of diagnoses differed by patient age and sex.

Methods: We used data from the National Ambulatory Medical Care Survey and the National Hospital Ambulatory Medical Care Survey to assess the rate of vitamin D deficiency diagnoses provided between 2007 and 2010 during outpatient visits with nonfederally employed physicians in offices and hospitals. Two hundred ninety-two unweighted patient visit records were included. Trends in vitamin D deficiency diagnosis over time, diagnosis of bone disease associated with a vitamin D deficiency diagnosis, and patient age and sex were reported.

Results: The number of diagnoses for vitamin D deficiency rapidly increased from 2007 to 2010. More than 97% of diagnoses were for unspecific vitamin D deficiency; 9.6% of vitamin D deficiency visits also resulted in a diagnosis of osteoporosis or bone fracture.

Conclusions: Although the rate of diagnoses for vitamin D deficiency increased between 2007 and 2010, many diagnoses rendered were for nonspecific disease; therefore, vitamin D deficiency screening may have been ordered for preventive care purposes rather than as a diagnostic aid.

Introduction

Osteomalacia in adults and rickets in children are the typical manifestations of clinical severe vitamin D deficiency.[1] Suggesting a greater public health concern than previously reported, clinicians and researchers, however, are more frequently investigating the relation between vitamin D deficiency and health outcomes such as cardiovascular disease, type 2 diabetes mellitus, fertility, and bone development.[2–5] Because much of this research is ongoing, the evidence linking vitamin D with benefits for nonskeletal outcomes has been inconsistent.[6]

Healthcare providers have reported confusion regarding the correct methods of testing target populations at high risk and clinically relevant definitions of vitamin D deficiency.[7–9] Although the 2011 Institute of Medicine (IOM) guidelines for vitamin D and calcium emphasize the importance of vitamin D in skeletal health and those and the guidelines published by the Endocrine Society agree that there is no need to screen the general population routinely, there is still disagreement between the two expert panels. The IOM emphasizes that 97.5% of the population are ensured bone health when levels of serum 25-hydroxyvitamin D (25[OH]D) are ≥20 ng/mL and defines vitamin D deficiency as <16 ng/mL.[6] The Endocrine Society defines vitamin D levels as sufficient at >30 ng/mL, insufficient between 21 and 29 ng/mL, and deficient at 20 ng/mL.[10]

It also is important that healthcare providers are aware of the variety of assay techniques available for the measurement of serum 25(OH)D concentrations. Liquid chromatography-tandem mass spectrometry is considered the gold standard,[11] but a variety of other assay kits are available, including the DiaSorin automated immunoassay test (DiaSorin, Saluggia, Italy), the IDS radioimmunoassay (IDS Ltd, Tyne and Wear, UK) and enzyme immunoassay, and automated protein binding assays. Compared with the gold standard, other tests can produce variable results and in some cases, systematically undermeasure serum 25(OH)D levels.[11,12]

Despite this controversy, research is ongoing and there is hope that this confusion will be eliminated as additional data better defining adequate vitamin D levels and health-related outcomes are reported. To help fill this gap in the research, data describing the trends in diagnosis of vitamin D deficiency are needed. Using a large annual nationally representative survey of outpatient department and office-based physicians, the objective of this investigation was to examine unspecific, general, and bone-related vitamin D deficiency diagnoses between 2007 and 2010 and to determine whether the rate of diagnoses differed by patient age and sex.

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